ADTRAN, Inc. Announces Revised First Quarter Revenue and Earnings Estimate

Business Wire, March 10, 2006

HUNTSVILLE, Ala. -- ADTRAN, Inc. (NASDAQ: ADTN) announced revised revenue and earnings estimates for the first quarter ending March 31, 2006. Based upon information currently available, revenue for the quarter is expected to range from $106 million to $112 million. GAAP earnings per share for the quarter, assuming dilution, are expected to range from $0.19 to $0.22. Pro forma earnings per share for the first quarter of 2006, assuming dilution, are expected to range from $0.21 to $0.24. Pro forma earnings per share for the first quarter exclude the effect of stock compensation expense resulting from the application of Statement of Financial Accounting Standards No. 123R, Share-Based Payment ("SFAS 123R"). SFAS 123R was adopted on a prospective basis effective January 1, 2006. See the table below for a reconciliation between GAAP earnings per share and non-GAAP pro forma earnings per share.

ADTRAN Chief Executive Officer Tom Stanton stated, "Our first quarter is normally affected by seasonality with booking rates typically increasing in the latter portion of the period. The increase in bookings activity normally experienced as we progress through the first quarter began later than anticipated, negatively impacting shipments. Overall, we believe our growth drivers remain in place and our outlook for the year has not changed."

The Company also confirmed that its first quarter conference call will be held Tuesday, April 18 at 9:30 a.m. Central Time. Guidance for the second quarter and year 2006 will be issued during this conference call. This conference call will be web cast live through StreetEvents.com. To listen, simply visit the Investor Relations site at http://www.adtran.com or http://streetevents.com approximately 10 minutes prior to the start of the call and click on the conference call link provided.

An online replay of the conference call will be available for seven days at http://streetevents.com. In addition, an online replay of the conference call, as well as the text of the Company's earnings release, will be available on the Investor Relations site at http://www.adtran.com for at least 12 months following the call.

ADTRAN, Inc. is one of the world's most successful network access equipment suppliers, with an 18-year history of profitability and a portfolio of more than 1,300 solutions for use in the last mile of today's telecommunications networks. Widely deployed by both carriers and enterprises, ADTRAN solutions enable voice, data, video, and Internet communications across copper, fiber, and wireless network infrastructures. ADTRAN solutions are currently in use by every major domestic service provider and many international ones, as well as by thousands of public, private and government organizations worldwide.

This press release contains forward-looking statements, which reflect management's best judgment based on factors currently known. However, these statements involve risks and uncertainties, including the successful development and market acceptance of new products, the degree of competition in the market for such products, the product and channel mix, component costs, manufacturing efficiencies, and other risks detailed in our annual report on Form 10-K for the year ended December 31, 2005. These risks and uncertainties could cause actual results to differ materially from those in the forward-looking statements included in this press release.

This release includes estimated non-GAAP pro forma earnings per share excluding the effect of stock compensation expense associated with the application of SFAS 123R, which ADTRAN adopted effective January 1, 2006. This measure is not in accordance with, or an alternative for, generally accepted accounting principles and may be different from non-GAAP (pro forma) measures used by other companies. ADTRAN believes that the presentation of the non-GAAP pro forma earnings per share data provides useful information to management and investors regarding financial and business trends relating to its financial condition and results of operations. In particular, as ADTRAN begins to apply SFAS 123R, it believes that it is useful to investors to understand how the expenses associated with the application of SFAS 123R are reflected in its anticipated results of operations. The presentation of non-GAAP pro forma earnings per share guidance permits both investors and management to more readily compare past results, which do not include the impact of SFAS 123R, with future results, and to better understand ADTRAN's performance over the periods presented.

Reconciliation of GAAP earnings per share estimate to
non-GAAP pro forma earnings per share estimate
(Unaudited)

                                                        First Quarter
                                                            2006
                                                       ---------------
                                                         Low     High
                                                       -------- ------
Estimated  GAAP earnings per common share, assuming
 dilution                                                $0.19  $0.22

Add:
   Estimated stock compensation expense under SFAS 123R   0.02   0.02
                                                       -------- ------

Estimated non-GAAP pro forma earnings per common share,
    assuming dilution                                    $0.21  $0.24
                                                       ======== ======