<HTML>
<HEAD>
<TITLE>
</TITLE>
</HEAD>
<BODY BGCOLOR="#FFFFFF" LINK=BLUE  VLINK=PURPLE>
<BR>
<FONT SIZE=3 ><A HREF="#02CHI2643_1">QuickLinks</A></FONT>
<font size=3> -- Click here to rapidly navigate through this document</font>
<P ALIGN="CENTER"><FONT SIZE=2><B>As filed with the Securities and Exchange Commission on April&nbsp;15, 2002  </B></FONT></P>

<P ALIGN="RIGHT"><FONT SIZE=2><B> Registration No.&nbsp;333-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </B></FONT></P>

<HR NOSHADE>
<HR NOSHADE>
<P ALIGN="CENTER"><FONT SIZE=5><B>SECURITIES AND EXCHANGE COMMISSION<BR>  </B></FONT><FONT SIZE=2><B>WASHINGTON, D.C. 20549  </B></FONT></P>

<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=5><B>FORM S-8<BR>  </B></FONT><FONT SIZE=2><B>REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933  </B></FONT></P>

<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=5><B>ALLEGIANCE TELECOM,&nbsp;INC.<BR>  </B></FONT><FONT SIZE=2>(Exact Name of Registrant as Specified in Its Charter) </FONT></P>

<!-- User-specified TAGGED TABLE -->
<TABLE WIDTH="100%" BORDER=0 CELLSPACING=0 CELLPADDING=0>
<TR VALIGN="TOP">
<TD WIDTH="50%" ALIGN="CENTER"><FONT SIZE=2><B>Delaware</B></FONT><FONT SIZE=2><BR>
(State or Other Jurisdiction of Incorporation or Organization)</FONT></TD>
<TD WIDTH="50%" ALIGN="CENTER"><FONT SIZE=2><B>75-2721491</B></FONT><FONT SIZE=2><BR>
(I.R.S. Employer Identification No.)</FONT></TD>
</TR>
</TABLE>
<!-- end of user-specified TAGGED TABLE -->

<P ALIGN="CENTER"><FONT SIZE=2><B>9201 Central Expressway<BR>
Dallas, Texas 75231<BR>  </B></FONT><FONT SIZE=2>(Address of Principal Executive Offices) (Zip Code) </FONT></P>

<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=5><B>ALLEGIANCE TELECOM,&nbsp;INC.<BR>
1998 STOCK INCENTIVE PLAN<BR>  </B></FONT><FONT SIZE=2>(Full Title of the Plan) </FONT></P>

<HR NOSHADE ALIGN="CENTER" WIDTH="120">
<P ALIGN="CENTER"><FONT SIZE=2><B>Mark B. Tresnowski<BR>
Senior Vice President, General Counsel and Secretary<BR>
Allegiance Telecom,&nbsp;Inc.<BR>
700 E. Butterfield Road, Suite 400<BR>
Lombard, Illinois 60148<BR>
(630)&nbsp;522-5200<BR>  </B></FONT><FONT SIZE=2>(Name and Address of Agent For Service; Telephone Number,<BR>
Including Area Code, of Agent for Service) </FONT></P>

<P ALIGN="CENTER"><FONT SIZE=2><B>CALCULATION OF REGISTRATION FEE  </B></FONT></P>

<!-- User-specified TAGGED TABLE -->
<TABLE WIDTH="100%" BORDER=0 CELLSPACING=0 CELLPADDING=0>
<TR VALIGN="TOP">
<TD COLSPAN=9 VALIGN="BOTTOM"><BR><HR NOSHADE></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="30%" ALIGN="CENTER" VALIGN="BOTTOM"><FONT SIZE=1><B>TITLE OF SECURITIES TO BE<BR>
REGISTERED</B></FONT></TD>
<TD WIDTH="1%" VALIGN="BOTTOM"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD WIDTH="20%" ALIGN="CENTER" VALIGN="BOTTOM"><FONT SIZE=1><B>AMOUNT TO BE<BR>
REGISTERED (1)</B></FONT></TD>
<TD WIDTH="1%" VALIGN="BOTTOM"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD WIDTH="15%" ALIGN="CENTER" VALIGN="BOTTOM"><FONT SIZE=1><B>PROPOSED MAXIMUM<BR>
OFFERING PRICE<BR>
PER SHARE</B></FONT></TD>
<TD WIDTH="1%" VALIGN="BOTTOM"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD WIDTH="15%" ALIGN="CENTER" VALIGN="BOTTOM"><FONT SIZE=1><B>PROPOSED MAXIMUM<BR>
AGGREGATE OFFERING<BR>
PRICE</B></FONT></TD>
<TD WIDTH="1%" VALIGN="BOTTOM"><FONT SIZE=1>&nbsp;</FONT></TD>
<TD WIDTH="17%" ALIGN="CENTER" VALIGN="BOTTOM"><FONT SIZE=1><B>AMOUNT OF<BR>
REGISTRATION<BR>
FEE</B></FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD COLSPAN=9 VALIGN="BOTTOM"><HR NOSHADE></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="30%"><FONT SIZE=2>Common Stock, par value $.01 per share</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="20%" ALIGN="CENTER"><FONT SIZE=2>2,000,000 shares</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="15%" ALIGN="CENTER"><FONT SIZE=2>$2.27(2)</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="15%" ALIGN="CENTER"><FONT SIZE=2>$4,540,000</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="17%" ALIGN="CENTER"><FONT SIZE=2>$418</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD COLSPAN=9 VALIGN="BOTTOM"><HR NOSHADE></TD>
</TR>
</TABLE>
<!-- end of user-specified TAGGED TABLE -->

<DL compact>
<DT style='margin-bottom:-11pt;'><FONT SIZE=2>(1)</FONT></DT><DD><FONT SIZE=2>Pursuant
to Rule&nbsp;416 of the Securities Act of 1933, this Registration Statement also covers such additional shares of common stock as may become issuable pursuant to possible
adjustments under the 1998 Stock Incentive Plan, as amended.
<BR><BR></FONT></DD><DT style='margin-bottom:-11pt;'><FONT SIZE=2>(2)</FONT></DT><DD><FONT SIZE=2>The
shares being registered hereby are additional shares reserved for issuance pursuant to the Allegiance Telecom,&nbsp;Inc. 1998 Stock Incentive Plan, as amended. Estimated
pursuant to Rule&nbsp;457(c) and (h)&nbsp;of the Securities Act of 1933, solely for purposes of calculating the amount of the registration fee, based upon the average of the high and low prices
reported for Allegiance Telecom's common stock on the Nasdaq National Market on April 12, 2002, of $2.27. </FONT></DD></DL>
<BR>
<HR NOSHADE>
<HR NOSHADE>
<HR NOSHADE>
<!-- ZEQ.=1,SEQ=1,EFW="2076969",CP="ALLEGIANCE TELECOM INC",DN="1",CHK=728816,FOLIO='blank',FILE='DISK021:[02CHI3.02CHI2643]BA2643A.;5',USER='SSTANSE',CD='15-APR-2002;15:15' -->
<!-- THIS IS THE END OF A COMPOSITION COMPONENT -->
<!-- TOC_END -->
<P ALIGN="CENTER"><FONT SIZE=2><A
NAME="de2643_explanatory_note"> </A>
<A NAME="toc_de2643_1"> </A>
<BR></FONT><FONT SIZE=2><B>EXPLANATORY NOTE    <BR>  </B></FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;This Registration Statement on Form&nbsp;S-8 is being filed by Allegiance Telecom,&nbsp;Inc., a Delaware corporation, in connection with the
registration of an additional 2,000,000 shares of our common stock, par value $.01 per share, issuable pursuant to the Fourth Amendment to the Allegiance Telecom,&nbsp;Inc. 1998 Stock Incentive
Plan. There is an effective registration statement relating to the issuance under this Plan of 8,766,333 shares of our common stock (Registration No.&nbsp;333-60486). There is an
effective registration statement relating to the issuance under this Plan of 6,000,000 shares of our common stock (Registration No.&nbsp;333-46866). There is an effective registration
statement relating to the issuance under this Plan of 3,739,627 shares of our common stock (Registration No.&nbsp;333-10402), after giving effect to a
three-for-two stock dividend on our common stock issued to stockholders on February&nbsp;28, 2000. There is an effective registration statement relating to the issuance under
this Plan of 5,494,040 shares of our common stock (Registration No.&nbsp;333-70769), after giving effect to a three-for-two stock dividend on our common stock
issued to stockholders on February&nbsp;28, 2000. All of these registration statements are incorporated by reference herein in accordance with General Instruction E to Form&nbsp;S-8.
In addition, in accordance with General Instruction E to Form&nbsp;S-8, this Registration Statement includes a facing page, this page, the signature page, an Exhibit Index, an
Exhibit&nbsp;5 legal opinion and Exhibit&nbsp;23 accountant's consent. </FONT></P>

<HR NOSHADE>
<!-- ZEQ.=1,SEQ=2,EFW="2076969",CP="ALLEGIANCE TELECOM INC",DN="1",CHK=314836,FOLIO='blank',FILE='DISK021:[02CHI3.02CHI2643]DE2643A.;2',USER='SSTANSE',CD='15-APR-2002;15:03' -->
<!-- THIS IS THE END OF A COMPOSITION COMPONENT -->
<!-- TOC_END -->
<P ALIGN="CENTER"><FONT SIZE=2><A
NAME="jc2643_signatures"> </A>
<A NAME="toc_jc2643_1"> </A>
<BR></FONT><FONT SIZE=2><B>SIGNATURES    <BR>  </B></FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form&nbsp;S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Dallas,
State of Texas, on April&nbsp;15, 2002. </FONT></P>

<!-- User-specified TAGGED TABLE -->
<TABLE WIDTH="78%" BORDER=0 CELLSPACING=0 CELLPADDING=0>
<TR VALIGN="TOP">
<TD WIDTH="47%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD COLSPAN=3><FONT SIZE=2>ALLEGIANCE TELECOM,&nbsp;INC.</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="47%"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="5%"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="45%"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="47%"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
<TD WIDTH="3%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="5%"><FONT SIZE=2><BR>
By:</FONT></TD>
<TD WIDTH="1%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="45%" ALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>ROYCE J. HOLLAND</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Royce J. Holland, </FONT><FONT SIZE=2><I>Chairman of the Board and Chief Executive Officer</I></FONT></TD>
</TR>
</TABLE>
<!-- end of user-specified TAGGED TABLE -->

<P ALIGN="CENTER"><FONT SIZE=2><B>POWER OF ATTORNEY  </B></FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Mark B. Tresnowski and Annie S. Terry, and each of them,
each with full power to act without the other, his true and lawful attorneys-in-fact and agents, each with full power of substitution and resubstitution, for such person and in
his name, place and stead, in any and all capacities, to sign any and all amendments or supplements to this Form&nbsp;S-8 Registration Statement and to file the same, with all exhibits
thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto each of said attorneys-in-fact and agents full power and
authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully as to all intents and purposes as he might or could do in person, hereby
ratifying and confirming all that each of said attorneys-in-fact and agents, or his or her substitutes, may lawfully do or cause to be done by virtue hereof. </FONT></P>

<P><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant
to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons on behalf of the Registrant and in the capacities
indicated on April&nbsp;15, 2002. </FONT></P>

<!-- User-specified TAGGED TABLE -->
<TABLE WIDTH="76%" BORDER=0 CELLSPACING=0 CELLPADDING=0>
<TR VALIGN="BOTTOM">
<TH WIDTH="47%" ALIGN="CENTER"><FONT SIZE=1><B>Signature</B></FONT><HR NOSHADE></TH>
<TH WIDTH="3%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="50%" ALIGN="CENTER"><FONT SIZE=1><B>Capacity</B></FONT><HR NOSHADE></TH>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>ROYCE J. HOLLAND</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Royce J. Holland</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Chairman of the Board and Chief Executive Officer (Principal Executive Officer)</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>C. DANIEL YOST</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> C. Daniel Yost</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
President, Chief Operating Officer and Director</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>THOMAS M. LORD</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Thomas M. Lord</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Executive Vice President, Chief Financial Officer and Director (Principal Financial Officer)</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>G. CLAY MYERS</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> G. Clay Myers</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Senior Vice President of Finance and Accounting (Principal Accounting Officer)</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>ANTHONY J. PARELLA</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Anthony J. Parella</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Executive Vice President and Director</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>JAMES E. CRAWFORD, III</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> James E. Crawford, III</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>JOHN B. EHRENKRANZ</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> John B. Ehrenkranz</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><BR><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
&nbsp;</FONT></TD>
</TR>
</TABLE>
<!-- insert table folio -->
<HR NOSHADE>
<!-- ZEQ.=1,SEQ=3,EFW="2076969",CP="ALLEGIANCE TELECOM INC",DN="1",CHK=822514,FOLIO='blank',FILE='DISK021:[02CHI3.02CHI2643]JC2643A.;3',USER='SSTANSE',CD='15-APR-2002;15:11' -->
<!-- end of table folio -->
<TABLE WIDTH="76%" BORDER=0 CELLSPACING=0 CELLPADDING=0>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>PAUL J. FINNEGAN</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Paul J. Finnegan</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>RICHARD D. FRISBIE</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Richard D. Frisbie</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>HOWARD I. HOFFEN</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Howard I. Hoffen</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>REED E. HUNDT</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Reed E. Hundt</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>ANDREW LIPMAN</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> Andrew Lipman</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
</TR>
<TR VALIGN="BOTTOM">
<TD WIDTH="47%" ALIGN="CENTER" VALIGN="CENTER"><FONT SIZE=2><BR>
/s/&nbsp;&nbsp;</FONT><FONT SIZE=2>JAMES N. PERRY, JR.</FONT><FONT SIZE=2>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT><HR NOSHADE><FONT SIZE=2> James N. Perry, Jr.</FONT></TD>
<TD WIDTH="3%" VALIGN="CENTER"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="50%" VALIGN="CENTER"><FONT SIZE=2><BR>
Director</FONT></TD>
</TR>
</TABLE>
<!-- end of user-specified TAGGED TABLE -->

<HR NOSHADE>
<!-- ZEQ.=2,SEQ=4,EFW="2076969",CP="ALLEGIANCE TELECOM INC",DN="1",CHK=458919,FOLIO='blank',FILE='DISK021:[02CHI3.02CHI2643]JC2643A.;3',USER='SSTANSE',CD='15-APR-2002;15:11' -->
<!-- THIS IS THE END OF A COMPOSITION COMPONENT -->
<!-- TOC_END -->
<P ALIGN="CENTER"><FONT SIZE=2><A
NAME="ka2643_index_to_exhibits"> </A>
<A NAME="toc_ka2643_1"> </A>
<BR></FONT><FONT SIZE=2><B>INDEX TO EXHIBITS    <BR>  </B></FONT></P>

<!-- User-specified TAGGED TABLE -->
<TABLE WIDTH="80%" BORDER=0 CELLSPACING=0 CELLPADDING=0>
<TR VALIGN="BOTTOM">
<TH WIDTH="12%" ALIGN="CENTER"><FONT SIZE=1><B>EXHIBIT<BR>
NUMBER</B></FONT><HR NOSHADE></TH>
<TH WIDTH="2%"><FONT SIZE=1>&nbsp;</FONT></TH>
<TH WIDTH="85%" ALIGN="CENTER"><FONT SIZE=1><B>DESCRIPTION</B></FONT><HR NOSHADE></TH>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2>4.1</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2>Form of certificate representing shares of Allegiance Telecom, Inc. common stock, $.01 par value per share, incorporated by reference to Exhibit 4.5 of its Registration Statement on Form S-1 (Registration File No.
333-53475)</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
4.2</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
Allegiance Telecom, Inc. 1997 Nonqualified Stock Option Plan, incorporated by reference to Exhibit 10.4 of its Registration Statement on Form S-4 (Registration File No. 333-49013)</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
4.3</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.6 of its Registration Statement on Form S-1 (Registration File No. 333-53475)</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
4.4</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
First Amendment to the Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.7 of its Form 10-K for the fiscal year ended December 31, 1998</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
4.5</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
Second Amendment to the Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.8 of its Form 10-K for the fiscal year ended December 31, 1999</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
4.6</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
Third Amendment to the Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.9 of its Form 10-K for the fiscal year ended December 31, 2000</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
4.7</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
Fourth Amendment to the Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.10 of its Form 10-K for the fiscal year ended December 31, 2001</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
*5.1</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
Opinion of Mark B. Tresnowski, the Senior Vice President, General Counsel and Secretary of Allegiance Telecom, Inc., with respect to the legality of the shares of the common stock being registered hereby</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
*23.1</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
Consent of Arthur Andersen LLP</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
*23.2</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
Consent of Mark B. Tresnowski (included in Exhibit 5.1)</FONT></TD>
</TR>
<TR VALIGN="TOP">
<TD WIDTH="12%" ALIGN="RIGHT"><FONT SIZE=2><BR>
*24</FONT></TD>
<TD WIDTH="2%"><FONT SIZE=2><BR>&nbsp;</FONT></TD>
<TD WIDTH="85%"><FONT SIZE=2><BR>
Power of Attorney (included in the signature pages of this Registration Statement)</FONT></TD>
</TR>
</TABLE>
<!-- end of user-specified TAGGED TABLE -->

<HR NOSHADE ALIGN="LEFT" WIDTH="120">
<DL compact>
<DT style='margin-bottom:-11pt;'><FONT SIZE=2>*</FONT></DT><DD><FONT SIZE=2>Filed
herewith. </FONT></DD></DL>
<HR NOSHADE>
<!-- ZEQ.=1,SEQ=5,EFW="2076969",CP="ALLEGIANCE TELECOM INC",DN="1",CHK=95846,FOLIO='blank',FILE='DISK021:[02CHI3.02CHI2643]KA2643A.;2',USER='SSTANSE',CD='15-APR-2002;15:10' -->
<!-- THIS IS THE END OF A COMPOSITION COMPONENT -->
<BR>
<P><br><A NAME="02CHI2643_1">QuickLinks</A><br></P><!-- TOC_BEGIN -->
<FONT SIZE=2><A HREF="#toc_de2643_1">EXPLANATORY NOTE</A></FONT><BR>
<!-- TOC_BEGIN -->
<FONT SIZE=2><A HREF="#toc_jc2643_1">SIGNATURES</A></FONT><BR>
<!-- TOC_BEGIN -->
<FONT SIZE=2><A HREF="#toc_ka2643_1">INDEX TO EXHIBITS</A></FONT><BR>
<!-- SEQ=,FILE='QUICKLINK',USER=MWEINST,SEQ=,EFW="2076969",CP="ALLEGIANCE TELECOM INC",DN="1" -->
<!-- TOCEXISTFLAG -->
</BODY>
</HTML>
[{"type": "S-8", "sequence": "1", "filename": "a2076969zs-8.htm", "description": "FORM S-8", "secsgml_size_bytes": 22603}]
{"company-data": {"conformed-name": "ALLEGIANCE TELECOM INC", "cik": "0001058703", "assigned-sic": "4813", "irs-number": "752721491", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-86260", "film-number": "02611075"}, "business-address": {"street1": "1950 STEMMONS FRWY", "street2": "STE 3026", "city": "DALLAS", "state": "TX", "zip": "75207", "phone": "2148537100"}, "mail-address": {"street1": "1950 STEMMONS FRWY", "street2": "STE 3026", "city": "DALLAS", "state": "TX", "zip": "75207"}}
QuickLinks
-- Click here to rapidly navigate through this document
As filed with the Securities and Exchange Commission on April 15, 2002
Registration No. 333-
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM S-8
REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
ALLEGIANCE TELECOM, INC.
(Exact Name of Registrant as Specified in Its Charter)
Delaware
(State or Other Jurisdiction of Incorporation or Organization)
75-2721491
(I.R.S. Employer Identification No.)
9201 Central Expressway
Dallas, Texas 75231
(Address of Principal Executive Offices) (Zip Code)
ALLEGIANCE TELECOM, INC.
1998 STOCK INCENTIVE PLAN
(Full Title of the Plan)
Mark B. Tresnowski
Senior Vice President, General Counsel and Secretary
Allegiance Telecom, Inc.
700 E. Butterfield Road, Suite 400
Lombard, Illinois 60148
(630) 522-5200
(Name and Address of Agent For Service; Telephone Number,
Including Area Code, of Agent for Service)
CALCULATION OF REGISTRATION FEE
TITLE OF SECURITIES TO BE
REGISTERED
AMOUNT TO BE
REGISTERED (1)
PROPOSED MAXIMUM
OFFERING PRICE
PER SHARE
PROPOSED MAXIMUM
AGGREGATE OFFERING
PRICE
AMOUNT OF
REGISTRATION
FEE
Common Stock, par value $.01 per share
2,000,000 shares
$2.27(2)
$4,540,000
$418
(1)
Pursuant
to Rule 416 of the Securities Act of 1933, this Registration Statement also covers such additional shares of common stock as may become issuable pursuant to possible
adjustments under the 1998 Stock Incentive Plan, as amended.
(2)
The
shares being registered hereby are additional shares reserved for issuance pursuant to the Allegiance Telecom, Inc. 1998 Stock Incentive Plan, as amended. Estimated
pursuant to Rule 457(c) and (h) of the Securities Act of 1933, solely for purposes of calculating the amount of the registration fee, based upon the average of the high and low prices
reported for Allegiance Telecom's common stock on the Nasdaq National Market on April 12, 2002, of $2.27.
EXPLANATORY NOTE
This Registration Statement on Form S-8 is being filed by Allegiance Telecom, Inc., a Delaware corporation, in connection with the
registration of an additional 2,000,000 shares of our common stock, par value $.01 per share, issuable pursuant to the Fourth Amendment to the Allegiance Telecom, Inc. 1998 Stock Incentive
Plan. There is an effective registration statement relating to the issuance under this Plan of 8,766,333 shares of our common stock (Registration No. 333-60486). There is an
effective registration statement relating to the issuance under this Plan of 6,000,000 shares of our common stock (Registration No. 333-46866). There is an effective registration
statement relating to the issuance under this Plan of 3,739,627 shares of our common stock (Registration No. 333-10402), after giving effect to a
three-for-two stock dividend on our common stock issued to stockholders on February 28, 2000. There is an effective registration statement relating to the issuance under
this Plan of 5,494,040 shares of our common stock (Registration No. 333-70769), after giving effect to a three-for-two stock dividend on our common stock
issued to stockholders on February 28, 2000. All of these registration statements are incorporated by reference herein in accordance with General Instruction E to Form S-8.
In addition, in accordance with General Instruction E to Form S-8, this Registration Statement includes a facing page, this page, the signature page, an Exhibit Index, an
Exhibit 5 legal opinion and Exhibit 23 accountant's consent.
SIGNATURES
Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Dallas,
State of Texas, on April 15, 2002.
ALLEGIANCE TELECOM, INC.
By:
/s/
ROYCE J. HOLLAND
Royce J. Holland,
Chairman of the Board and Chief Executive Officer
POWER OF ATTORNEY
KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Mark B. Tresnowski and Annie S. Terry, and each of them,
each with full power to act without the other, his true and lawful attorneys-in-fact and agents, each with full power of substitution and resubstitution, for such person and in
his name, place and stead, in any and all capacities, to sign any and all amendments or supplements to this Form S-8 Registration Statement and to file the same, with all exhibits
thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto each of said attorneys-in-fact and agents full power and
authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully as to all intents and purposes as he might or could do in person, hereby
ratifying and confirming all that each of said attorneys-in-fact and agents, or his or her substitutes, may lawfully do or cause to be done by virtue hereof.
Pursuant
to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons on behalf of the Registrant and in the capacities
indicated on April 15, 2002.
Signature
Capacity
/s/
ROYCE J. HOLLAND
Royce J. Holland
Chairman of the Board and Chief Executive Officer (Principal Executive Officer)
/s/
C. DANIEL YOST
C. Daniel Yost
President, Chief Operating Officer and Director
/s/
THOMAS M. LORD
Thomas M. Lord
Executive Vice President, Chief Financial Officer and Director (Principal Financial Officer)
/s/
G. CLAY MYERS
G. Clay Myers
Senior Vice President of Finance and Accounting (Principal Accounting Officer)
/s/
ANTHONY J. PARELLA
Anthony J. Parella
Executive Vice President and Director
/s/
JAMES E. CRAWFORD, III
James E. Crawford, III
Director
/s/
JOHN B. EHRENKRANZ
John B. Ehrenkranz
Director
/s/
PAUL J. FINNEGAN
Paul J. Finnegan
Director
/s/
RICHARD D. FRISBIE
Richard D. Frisbie
Director
/s/
HOWARD I. HOFFEN
Howard I. Hoffen
Director
/s/
REED E. HUNDT
Reed E. Hundt
Director
/s/
ANDREW LIPMAN
Andrew Lipman
Director
/s/
JAMES N. PERRY, JR.
James N. Perry, Jr.
Director
INDEX TO EXHIBITS
EXHIBIT
NUMBER
DESCRIPTION
4.1
Form of certificate representing shares of Allegiance Telecom, Inc. common stock, $.01 par value per share, incorporated by reference to Exhibit 4.5 of its Registration Statement on Form S-1 (Registration File No.
333-53475)
4.2
Allegiance Telecom, Inc. 1997 Nonqualified Stock Option Plan, incorporated by reference to Exhibit 10.4 of its Registration Statement on Form S-4 (Registration File No. 333-49013)
4.3
Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.6 of its Registration Statement on Form S-1 (Registration File No. 333-53475)
4.4
First Amendment to the Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.7 of its Form 10-K for the fiscal year ended December 31, 1998
4.5
Second Amendment to the Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.8 of its Form 10-K for the fiscal year ended December 31, 1999
4.6
Third Amendment to the Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.9 of its Form 10-K for the fiscal year ended December 31, 2000
4.7
Fourth Amendment to the Allegiance Telecom, Inc. 1998 Stock Incentive Plan, incorporated by reference to Exhibit 10.10 of its Form 10-K for the fiscal year ended December 31, 2001
*5.1
Opinion of Mark B. Tresnowski, the Senior Vice President, General Counsel and Secretary of Allegiance Telecom, Inc., with respect to the legality of the shares of the common stock being registered hereby
*23.1
Consent of Arthur Andersen LLP
*23.2
Consent of Mark B. Tresnowski (included in Exhibit 5.1)
*24
Power of Attorney (included in the signature pages of this Registration Statement)
*
Filed
herewith.
QuickLinks
EXPLANATORY NOTE
SIGNATURES
INDEX TO EXHIBITS