The Multicall supplementary service enables a mobile subscriber to have several simultaneous CS calls, each call using its own dedicated bearer.
Only one CS bearer can used for speech at a given time.
A speech call is one of TS11 (Telephony), TS12 (Emergency Calls), and TS61 (Alternate speech/fax). If the bearer
capability information is not available, e.g. the call is originated/transited by a PSTN, the basic service cannot be deduced and the network shall, for multicall purposes, handle the call as telephony.
A held call shall be regarded as using the bearer used while the call was active.
Note: The 3GPP protocol architecture allows several parallel CS calls, the limitation being that there is only one
traffic channel in GERAN, which the different CS calls share. This is facilitated by e.g. the Call Waiting,
Call Hold, Call Transfer and Multiparty Supplementary Services. Call configurations related to
supplementary services are not considered as Multicall. See clause 7 for interaction.
It shall be possible for each CS call to use a dedicated bearer of independent traffic and performance characteristics. It shall be possible to release each active CS call independently of any other CS call.