This number (215-987-5366) calls my office every day. When I pick up, the call disconnects. When I call back, it rings once, and then the call disconnects.
They are still at it. Probably a blind robodialer, if too many people answer there are no agents to connect so it lets you hanging as many folks describe. Most of these seem to be about security systems from ADT. ADT is part of Tyco. Remember Tyco? Their ex-CEO is doing 8 to 25 in Rikers for assorted fraud charges.