Method for improving telephone resource access in a communication system network

In a communication system network, a communication unit may maintain allocation of a telephone resource when it roams into another communication system. Having established a communication in a first communication system, the communication unit is allocated a communication resource in the first communication system and is also allocated a telephone resource. While the communication unit is allocated the communication resource and the telephone resource, it determines whether the transceiving quality of the allocated communication resource has degraded below a predetermined level. When the transceiving quality has degraded below a predetermined level, the communication unit transmits a registration packet to second communication system via the central controller. Upon receiving the registration packet, the central controller reclaims the allocated communication resource in the first communication unit and attempts to allocate a communication resource in the second communication system. When the second communication system does not have an available communication resource, the central controller maintains the allocation of the telephone resource to the communication unit until a communication resource becomes available in the second communication system.