5.8 Modification Procedures

23.1533GPPOut of band transcoder controlRelease 17Stage 2TS

The OoBTC procedures shall support the following modification mechanisms:

i) Modification of Selected Codec.
(The codec type of the Selected Codec (BICC) may be switched to another type within the Available Codecs List (BICC), and/or the Active Codec mode Set of the Selected Codec (BICC) may be modified, and/or the Supported Codec mode Set of the Selected Codec (BICC) may be reduced.)

ii) Modification of Available Codecs List
(The Available Codecs List (BICC) may be reduced by removing codec types and modes)

iii) Mid-call Codec Negotiation
(The Available Codec List (BICC) is re-negotiated, allowing the addition and removal of codec types and modes compared to the previous Available Codec List (BICC), and a new Selected Codec (BICC) is chosen out of the new Available Codec List (BICC))

The specific call flows when such procedures may be required are detailed in Clause 6. Further information on the Available Codecs List (BICC) and the Selected Codec (BICC) is provided in clause 5.2. Further information on codec types, codec modes, a Supported Codec mode Set and an Active Codec mode Set is provided in TS 26.103 [5]. The basic codec negotiation principles are defined by the BICC Call Control Procedures (see [6]) but the explicit Mc interface procedures are added.