The phone number belongs to a gated comminity's outside visitors call box. People look up the tenants in the community and then the tenants can buzz them in.

i got a call around 1130 last nite and it left me a voicemail. but there was no one talking...it just sounded like a generator was going on in the backround. and so i called it this morning at 730 an the same noise came on and there was no one on the other line