Systems, methods, devices, and computer program products are described for using an out-of-band (OOB) radio integrated with the femtocell to implement various novel proximity detection techniques. Proximity detection of access terminals (ATs) in the femtocell's access control list (ACL) can be desirable to support femto connectivity and service provision, for example, in context of idle macro-to-femto handoffs, active macro-to-femto hand-ins, etc. Implementations implement OOB proximity detection through multicasting directed proximity request messages to each AT in a femtocell's ACL. Responses to the proximity request message can include identification information used to determine the specific AT that is in proximity.