An initial channel access message such as a Random Access Channel (RACH) preamble is used to mean that not only that a channel access has been requested by a mobile station (500) but also that a particular type of service has been requested. By associating a type of service (e.g., Dispatch, web browsing, etc.) with the particular signature that is used to form the RACH preamble it speeds up the service negotiation process. Both the communication system (600) and the MS (500) know what service is associated with which signature, so as soon as a RACH preamble is received by the system, it can determine if it has the resources available to accommodate the request.