03 Decline. Service Profiles 5.2.1.7.2. OCB Outgoing communication barring (OCB) is able to block an outgoing communication belonging to a certain category of communication. Bob's telephony application server responds to Alice's UA entity with the message 603 Decline. 5.2.1.7.3. ACR Anonymous communication rejection (ACR) enables Bob to reject an anonymous communication. Bob's TAS entity rejects the communication because the INVITE request contains the header Privacy with the value id. It responds to the INVITE request with the message 433 Anonymity Disallowed. 5.2.2. Audio flow The SDP message contains the types of audio codecs proposed by the caller and the codec selected by the callee, among the following list of codecs: - adaptative multi-rate (AMR); - AMR-WB (Wide Band); - enhanced voice services (EVS). 5.2.2.1. AMR codec The AMR codec provides the analog/digital conversion of an audio signal in the frequency band 300-3400 Hz. The AMR codec produces 20 ms frames and the resulting flow can have the following values: 12.2 kbps, 10.2 kbps, 7.95 kbps, 7.40 kbps, 6.70 kbps, 5.90 kbps, 5.15 kbps and 4.75 kbps. The AMR codec uses discontinuous transmission (DTX) associated with voice activity detection (VAD) and comfort noise generation (CNG) to reduce the flow rate during periods of silence. The SDP offer contains the values of the payload type field of the real- time transport protocol (RTP) header that identifies the codec type used. VoLTE and ViLTE m=audio 49152 RTP/AVP 97 98 a=rtpmap : 97 AMR/8000/1 a=rtpmap 98 AMR/8000/1 a=fmtp : 98 octet-align=1 The value 97 corresponds to the bandwidth-efficient format, for which only the payload is aligned on byte boundaries, fewer padding bits being thus added. The value 98 corresponds to byte-aligned format, where all fields in the payload of the RTP segment are aligned individually on byte boundaries (a = fmtp: 98 byte-align = 1). The value of 97 for the payload type field is listed first as the corresponding format has priority. 5.2.2.2. AMR-WB codec The AMR-WB codec h