Section: 5.3.6.3 In-call modification in the "active" state
Content: The in-call modification procedure as described in subclause 5.3.4.3 shall be used to: - trigger a service change between speech and UDI/RDI multimedia modes, when service change has been agreed at call setup; - trigger a network-initiated service upgrade from speech to UDI/RDI multimedia modes (see 3GPP TS 23.172[ Technical realization of Circuit Switched (CS) multimedia service UDI/RDI fallback and service modification; Stage 2 ]  [97]). The network shall initiate this procedure only if the mobile station indicated support of the enhanced network-initiated in-call modification procedure in the Call Control Capabilities IE at call establishment. In this case, the MODIFY message shall include the Network-initiated Service Upgrade indicator IE; or - modify the multimedia bearer capability for an analogue multimedia call (restricted to the network initiated in-call modification only). In this case, the network shall send a MODIFY message including the new Bearer Capability to be changed to. The following bearer capability parameters can be modified with the procedure (see 3GPP TS 29.007[ General requirements on interworking between the Public Land Mobile Network (PLMN) and the Integrated Services Digital Network (ISDN) or Public Switched Telephone Network (PSTN) ]  [38]): - Fixed Network User Rate (analogue multimedia calls only).