[ARCHIVE ANSWER]
If a 911 call comes from a house, kops have a right to enter. The probable cause is the 911 call. Ninety-nine percent of the time they will enter the home but as you said you do not have a home phone. However, the police have caller I.D even on private calls. They should have confirmed the phone number first. Anyone with a grudge can dial 911 and say something happened.