Section: 5.3.4.4 Abnormal procedures
Content: If a MODIFY, MODIFY COMPLETE or MODIFY REJECT message is received in the "disconnect indication", "disconnect request" (mobile station side only) or "release request" state then the received message shall be discarded and no action shall be taken. If a MODIFY COMPLETE message indicating a call mode which does not correspond to the requested one is received or if a MODIFY REJECT message indicating a call mode which does not correspond to the actual one is received then the received message shall be discarded and no action shall be taken. If a MODIFY message indicating a call mode which does not belong to those negotiated and agreed during the establishment phase of the call, is received, then a MODIFY REJECT message with the actual call mode and with cause # 57 "bearer capability not authorized" shall be sent back. Figure 5.10a/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  In-call modification sequence initiated by MS Figure 5.10b/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  In-call modification sequence initiated by network