The circuit switched multicall service in UMTS

The current second-generation cellular mobile networks provide for each user only one simultaneous circuit switched connection. A GSM user can control more than one speech call only by using supplementary service Call Hold (CH). In a CH situation, a user may keep only one call in an active state, while the other calls are on hold [9]. Also with GSM's multiple time slot connections, HSCSD (High Speed Circuit Switched Data), all the time slots are assigned for one user data traffic channel which cannot be used for multicall purpose [1]. In this paper we present multicall concept of the UMTS designed in 3GPP (3:rd Generation Partnership Project) to utilize the wide bandwidth with a new type of user service. This will allow a user to control several simultaneous circuit-switched traffic channels by a single terminal. Parallel traffic channels can be activated dynamically and independently, and their use is not limited to speech or data only. The multicall service can be implemented with minor modifications to the existing GSM Connection Management protocols on which the UMTS Connection Management layer is based.