A machine, such as a mobile device having telephony features, such as a voice over Internet Protocol (VoIP) telephony application, is configured with a secure environment in which a location provider within (more reliable) or external to (less reliable) the machine may determine location data for the machine and securely provide it to a telephony application program for incorporation into a call setup for calling a callee. The secure environment may be created through use of one or more of Intel's LaGrande Technology™ (LT), Vanderpool Technology (VT), or a Trusted Platform Module (TPM). The LT and VT allow defining secure independent components within the machine, such as by instantiating them as Virtual Machines, and the TPM allows components to cryptographically sign data, such as to facilitate ensuring the location data is not tampered with. A recipient of a telephone call setup including cryptographically secured location data may validate the location data and accept the call. Other embodiments may be described.