1. A method of communication in a communication network including first and second network entities, said method comprising: receiving at the second network entity at least one message communicated over-the-air by the first network entity, said at least one message including a first field and a second field, wherein the first field is set to a value indicating support by the first network entity for concurrent over-the-air voice and packet data service instances with the second network entity, and the second field is set to indicate a number of the concurrent over-the-air voice and packet data service instances supported by the first network entity, and wherein each packet data service instance includes a session to communicate packet data, and wherein each voice service instance includes a session to communicate voice; and said second network entity limiting a number of concurrent over-the-air voice and packet data service instances requested by the second network entity in accordance with the second field in said at least one message.