The Defense Ministry, in announcing the return of mobile phone service to Adamawa, said there had been "positive indications" about security in the state, the BBC reported Friday.
There have been safety concerns about the lack of cellphone service in some areas.
Last week, after an attack in Yobe state killed 22 students and a teacher, Yobe Gov. Ibrahim Gaidam said the absence of phone service had prevented the public from "reporting suspicious movements in their neighborhoods."
Adamawa has been the state least affected by attacks from the Islamic group Boko Haram.
Cellphone service in Yobe and Borno states was still blocked.