POWER OF ATTORNEY
KNOW ALL MEN BY THESE PRESENTS, that the undersigned constitutes and appoints
James E. Matthews, Cathy Bartels, and Gayle Ellis,
and each of them, his true and lawful attorneys-in-fact and agents, with full
power of substitution, for him and in his name, place
and stead, in any and all capacities, to:
1. Execute for and on behalf of the undersigned, in the undersigned's capacity
as an officer and/or director of ADTRAN, Inc.
(the "Company"), Forms 3, 4 and 5 in accordance with Section 16(a) of the
Securities Exchange Act of 1934, as amended, and the rules
thereunder;
2. do and perform any and all acts for and on behalf of the undersigned which
may be necessary or desirable to complete
and execute any such Form 3, 4 or 5 and timely file such form with the United
States Securities and Exchange Commission and any
stock exchange or similar authority; and
3. take any other action of any type whatsoever in connection with the foregoing
which, in the opinion of such attorney-in-fact,
may be of benefit to, in the best interest of, or legally required by, the
undersigned, it being understood that the documents executed
by such attorney-in-fact on behalf of the undersigned pursuant to this Power of
Attorney shall be in such form and shall contain such
terms and conditions as such attorney-in-fact may approve in such
attorney-in-fact's discretion.

The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing
whatsoever requisite, necessary, or proper to be done in the exercise of any of
the rights and powers herein granted, as fully to all
intents and purposes as the undersigned might or could do if personally present,
with full power of substitution or revocation, hereby
ratifying and confirming all that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, shall lawfully do or cause
to be done by virtue of this power of attorney and the rights and powers herein
granted.

The undersigned acknowledges that the foregoing attorneys-in-fact, in serving in
such capacity at the request of the undersigned,
are not assuming, nor is the Company assuming, any of the undersigned's
responsibilities to comply with Section 16 of the Securities
Exchange Act of 1934. This Power of Attorney shall remain in full force and
effect until the undersigned is no longer required to file
Forms 3, 4 and 5 with respect to the undersigned's holdings of and transactions
in securities issued by the Company, unless earlier revoked
by the undersigned in assigned writing delivered to the foregoing
attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 5th day of May, 2010.

P. Steven Locke        May 5,2010