A method (70) and system (11) of determining a destination can include obtaining (72) at least one identifier among a phone number, a dispatch identifier, a mobile internet protocol address, an instant messaging user identifier, an e-mail address, or other identifier having mobility management information, mapping (74) the at least one identifier to an approximate physical location, and selectively retrieving (76) the approximate physical location corresponding to the at least one identifier. For example, mapping can be done by mapping the phone number to a physical address provided by white pages or yellow pages from on-line phonebooks or by mapping to location services (such as GPS or network based locating services) available at a cellular phone, dispatch radio, or wireless internet protocol device. Mapping can include mapping at least one among the IM user identifier or the e-mail address to a PSTN, a dispatch identifier or an internet protocol address.