Techniques for selecting positioning protocols consistent with the capabilities of the location server in a Secure User Plane Location (SUPL) based service are described. The SUPL Location Platform (SLP) transmits the service capabilities of the SLP, such as the positioning protocol capabilities of the SLP. The SLP transmits its capabilities of the SLP in an initiation message to the SUPL enabled terminal (SET) or after receiving an initiation message from the SET. The SET may transmit a positioning initiation message and the SLP and SET communicate to determine one or more position estimates for the SET. The SET may include in the positioning initiation message a positioning protocol positioning message that is consistent with the SLP service capabilities.