10.9 IWF as a security gateway

23.2833GPPMission Critical Communication Interworking with Land Mobile Radio SystemsRelease 18TS

10.9.1 Support for transcoding with encrypted speech

In some cases when encryption of voice media is required in the MC system, the MCPTT user(s) and the LMR user(s) can use different codecs. In these cases, transcoding is needed and before transcoding can occur, encryption applied to the voice media by the MC system needs to be removed. After transcoding, LMR encryption can be applied (out-of-scope of the present document). An IWF can perform these functions and be deployed as a security gateway between the MCPTT system and the LMR system. When the IWF removes the encryption applied by the MC system, the IWF must perform key management procedures defined in 3GPP TS 33.180 [8] to obtain the key material for the group.