A suicidal man called 911 from a TriBeCa pay phone yesterday to tell cops he murdered his girlfriend in her Bronx apartment, authorities said.

The unidentified suspect made the call in front of 140 Church St. at around 6:40 p.m., saying he wanted to kill himself, and then gave an address in Soundview where his dead girlfriend was later found, cops said.

When police arrived at the payphone, the man had fled.

The woman was found brutally beaten on the head — and she appeared to have been killed several days ago, cops said.