10-K405/A

QuickLinks -- Click here to rapidly navigate through this document

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 10-K/A

(Mark One)

ý	ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the fiscal year ended December 31, 2001
OR

o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
SECURITIES EXCHANGE ACT OF 1934

Commission file number 001-14157

TELEPHONE AND DATA SYSTEMS, INC.
(Exact name of registrant as specified in its charter)

Delaware	36-2669023
(State or other jurisdiction of incorporation or organization)	(IRS Employer Identification No.)
30 North LaSalle Street, Chicago, Illinois	60602
(Address of principal executive offices)	(Zip code)
Registrant's Telephone Number:    (312) 630-1900
Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Name of each exchange on which registered
Common Shares, $.01 par value	American Stock Exchange
8.5% TDS-Obligated Mandatorily Redeemable Preferred Securities of Subsidiary Trust	American Stock Exchange
8.04% TDS-Obligated Mandatorily Redeemable Preferred Securities of Subsidiary Trust	American Stock Exchange
7.60% Series A Notes due 2041	New York Stock Exchange
Securities registered pursuant to Section 12(g) of the Act:    None

        Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Yes  X   No   

        Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  X 

        As of February 28, 2002, the aggregate market values of the registrant's Common Shares, Series A Common Shares and Preferred Shares held by non-affiliates were approximately $4.490 billion, $37.2 million and $20.1 million, respectively. The closing price of the Common Shares on February 28, 2002, was $87.15, as reported by the American Stock Exchange. Because no market exists for the Series A Common Shares and Preferred Shares, the registrant has assumed for purposes hereof that (i) each Series A Common Share has a market value equal to one Common Share because the Series A Common Shares were initially issued by the registrant in exchange for Common Shares on a one-for-one basis and are convertible on a share-for-share basis into Common Shares, (ii) each nonconvertible Preferred Share has a market value of $100 because each of such shares had a stated value of $100 when issued, and (iii) each convertible Preferred Share has a value of $87.15 times the number of Common Shares into which it was convertible on February 28, 2002.

        The number of shares outstanding of each of the registrant's classes of common stock, as of February 28, 2002, is 51,824,928 Common Shares, $.01 par value, and 6,775,973 Series A Common Shares, $.01 par value.

DOCUMENTS INCORPORATED BY REFERENCE

        Those sections or portions of the registrant's 2001 Annual Report to Shareholders and of the registrant's Notice of Annual Meeting of Shareholders and Proxy Statement for its Annual Meeting of Shareholders to be held May 23, 2002, described in the cross reference sheet and table of contents attached hereto are incorporated by reference into Part II and III of this report.

EXPLANATORY NOTE

        This amendment to Form 10-K is being filed for the sole purpose of filing as Exhibit 99 a letter of assurances with respect to Arthur Andersen, LLP prescribed by Temporary Note 3T of Rule 3-01 of Regulation S-X adopted by Release no. 33-8070 issued by the Securities and Exchange Commission.

        The following document is hereby added to the "INDEX TO EXHIBITS" and is attached hereto.

Exhibit No.	Description of Document
99	Letter pursuant to Temporary Note 3T of Rule 3-01 of Regulation S-X

SIGNATURES

        Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

TELEPHONE AND DATA SYSTEMS, INC.
By:	/s/  LEROY T. CARLSON, JR.
	LeRoy T. Carlson, Jr. President, (Chief Executive Officer)
By:	/s/  SANDRA L. HELTON
	Sandra L. Helton Executive Vice President (Chief Financial Officer)
By:	/s/  D. MICHAEL JACK
	D. Michael Jack Vice President and Controller (Principal Accounting Officer)

Dated March 27, 2002

        Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Signature	Title	Date
/s/  LEROY T. CARLSON LeRoy T. Carlson	Director	March 27, 2002
/s/  LEROY T. CARLSON, JR. LeRoy T. Carlson, Jr.	Director	March 27, 2002
/s/  SANDRA L. HELTON Sandra L. Helton	Director	March 27, 2002
/s/  JAMES BARR III James Barr III	Director	March 27, 2002
/s/  WALTER C.D. CARLSON Walter C.D. Carlson	Director	March 27, 2002
/s/  LETITIA G.C. CARLSON Letitia G.C. Carlson	Director	March 27, 2002
/s/  HERBERT S. WANDER Herbert S. Wander	Director	March 27, 2002
/s/  DONALD C. NEBERGALL Donald C. Nebergall	Director	March 27, 2002
/s/  GEORGE W. OFF George W. Off	Director	March 27, 2002
/s/  MARTIN L. SOLOMON Martin L. Solomon	Director	March 27, 2002
/s/  KEVIN A. MUNDT Kevin A. Mundt	Director	March 27, 2002
/s/  MICHAEL D. BILLS Michael D. Bills	Director	March 27, 2002

QuickLinks

SIGNATURES

EX-99

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 99

Telephone and Data Systems, Inc.
30 North LaSalle Street
Suite 4000
Chicago, Illinois 60602

March 27, 2002

Securities and Exchange Commission
450 Fifth Street, N.W.
Judiciary Plaza
Washington, DC 20549

        Re:    Confirmation of Arthur Andersen, LLP Representations

Ladies and Gentlemen:

        Pursuant to Temporary Note 3T to Article 3 of Regulation S-X, Telephone and Data Systems, Inc. (the "Company") has obtained a letter of representation from Arthur Andersen LLP ("Andersen"), the independent public accountant engaged by the Company to examine the Company's financial statements (the "Financial Statements") that are included in the Form 10-K to which this letter is filed as an exhibit, stating that:

•

the audit of the Financial Statements was subject to Andersen's quality control system for the U.S. accounting and auditing practice to provide reasonable assurance that the engagement was conducted in compliance with professional standards; and



•

there was appropriate continuity of Andersen personnel working on the audit and availability of national office consultation. Availability of personnel at foreign affiliates of Andersen is not relevant to this audit.

Very truly yours,

TELEPHONE AND DATA SYSTEMS, INC.


By: /s/ D. Michael Jack    Name: D. Michael Jack
    Title: Vice President and Controller
          (Principal Accounting Officer)

QuickLinks

Exhibit 99
Telephone and Data Systems, Inc. 30 North LaSalle Street Suite 4000 Chicago, Illinois 60602 March 27, 2002