Section: B.3.2 Network-to-MS compatibility checking
Content: When the network is providing a basic service at the called side, the MS shall check that the basic service(s) offered by the network in the Bearer Capability information element(s) match(es) the basic services that the MS is able to support. If a mismatch is detected, then the MS shall proceed as follows: - if the SETUP message contained two bearer capability information elements for only one of which a mismatch is detected, the MS shall either: - under the conditions specified in 3GPP TS 27.001[ General on Terminal Adaptation Functions (TAF) for Mobile Stations (MS) ]  [36] (e.g. TS 61 and TS 62), accept the SETUP message with a CALL CONFIRMED message containing the, possibly negotiated, bearer capability information element for which no mismatch is detected, or - reject the call using cause No. 88 "incompatible destination". - otherwise the MS shall reject the offered call using a RELEASE COMPLETE message with cause No. 88 "incompatible destination". NOTE: The backup bearer capability IE is not subject to compatibility checking. When interworking with existing networks, limitations in network or distant user signalling (e.g. in the case of an incoming call from a PSTN or a call from an analogue terminal) may restrict the information available to the called MS in the incoming SETUP message (e.g. missing Bearer Capability Information Element or missing High Layer Compatibility Information Element). For compatibility checking, and handling of such calls see 3GPP TS 27.001[ General on Terminal Adaptation Functions (TAF) for Mobile Stations (MS) ]  [36].