Jerome Cushing, 37, was arrested earlier this week after the alleged victim called police.
According to the Bangor Daily News, the woman claims Cushing was upset because she hadn't been answering his calls.
She says he came to her home about a month ago and came into her bedroom, where he sexually assaulted her with the phone. She also claimed he had hit her many times over the past year and a half.
Cushing was arrested Monday and is charged with gross sexual assault and two counts of domestic violence assault. He has denied the allegations and is being held in the Knox County Jail on $1,500 bail.