Procedure for exchanging useful information generated according to different coding laws between at least 2 pieces of user terminal equipment

摘要

If TDM connections are through-connected from the originating TDM network to the target TDM network via a data network in the form of backbone, e.g. VoIP, the switchover between the TDM network and the data network takes place via media gateways. As is the case with connections exclusively between TDM, the coding algorithms of the A face and the B face have to be identical. In TDM networks, coding is done according to A Law and μ Law. When switching from an A Law network to a μ Law network, the coding specifications have to be converted. In order to carry out a conversion in a TDM environment, at the switchover point the μ Law face has to convert to A Law. The same applies to VoIP. The invention relates to the integration of this switchover conversion rule in the codec negotiation procedure so that in principle a μ Law A face offers μ Law and, alternatively, A-Law to the B face; a μ Law B face accepts μ Law whereas an A-Law B face acknowledges A-Law. Furthermore, 64 kBit/s unrestricted preferred connections are considered in fall back mode, wherefore an additional logic is integrated into the codec modification procedure by means of which in principle μ Law and, as an alternative, A-Law are offered to the B face in addition to the transparent CODEC or instead of offering a μ Law A face to the TMR only. The B face first accepts the transparent CODEC on the basis of the list or the TMR ‘64 kBit/s unrestricted preferred’. When receiving the TMU, the B face selects the Codec to satisfy the code conversion rule.