Tel number is (800) 375-5283
Here is the fax number I used for address change.
Employment-Based Services: Fax (214) 962-5520
Adjustment Services: Fax (214) 962-5103
There is special P.O.BOX number for mailing address change.
BCIS TSC
P.O. Box 850891
Mesquite, TX 75185-0891
Use thi link for reference.
http://www.bcis.gov/graphics/fieldoffices/texas/aboutus.htm
http://www.bcis.gov/graphics/publicaffairs/newsrels/address.htm
http://www.bcis.gov/graphics/howdoi/address.htm
Change of Address:
For Naturalization Applications:
Customers with pending applications for naturalization (Form N-400) may report their change of address to the NCSC toll-free at 1 (800) 375-5283 instead of submitting the change in writing. Currently, only applications for naturalization may change their address by phone.
For All Other Applications:
Customers may report a change of address for any other application submitted to this office by sending a letter to this Service Center. Please use the following address:
BCIS TSC
P.O. Box 850891
Mesquite, TX 75185-0891
Please include in the letter:
Your name as it appears in the application
Your 8 or 9 digit A-number
Your OLD and NEW address
Clearly mark your letter "ATTENTION: CHANGE OF ADDRESS"
All persons reporting a change of address must file Form AR-11.