Standardization, Conclusion, References

frame-bundling feature is supported in the AMR and EVRC payload format. Built-in functionality in the MRF makes it possible to order clients to change the number of frames in an RTP packet to adapt to current network conditions. The MRF employs the RTP control protocol (RTCP) to monitor the network.

Standardization

The Ericsson Instant Talk solution is based on the PoC industry standard, initially de- veloped by an industry consortium made up of Ericsson, Motorola, Nokia, and Siemens mobile, and supported by AT&T Wireless Services, Cingular, Sonim Tech- nologies, and Sony Ericsson. It is an open, published and demonstrated interoperable multi-vendor specification. PoC Phase I in- cludes detailed specifications that mandate the requirements and architecture of the solution. In additon to the Stage 1 and 2 specifications, the consortium also devel- oped a complete Stage 3 suite of PoC spec- ifications that stipulate signaling flows, user-plane flows (including talk burst con- trol mechanisms), and group and list man- agement methods. One of the specifica- tions applies specifically to the radio access network, describing the recommended QoS attributes of the radio link and the op- eration of the voice codec. To avoid mar- ket segmentation, Ericsson has striven for an open standard that avoids lock-in and creates interoperability between operators and between terminals from different ven- dors.

Ericsson and the other members of the consortium have submitted the Phase 1 specification to OMA. The OMA process is moving forward, and the PoC Phase 1 spec- ification has formed a basis for the OMA PoC standard. Further development will in- clude new features in the PoC specifications, such as a standardized presence solution (Figure 3), an enhanced authentication

Figure 3

Mobile presence makes everyday communication easier.

method, and a network-to-network inter- face to enable charging between operators and to make the PoC solution compatible with additional radio access networks (WCDMA and CDMA2000). As the OMA PoC standard evolves, the Ericsson Instant talk product will be updated.

Conclusion

Ericsson Instant Talk is the first of many IP- based applications that will be available over IPMM, which is based on the 3GPP IMS standard. The applications running on IPMM are controlled using SIP and SigComp (to make SIP efficient in mobile communications).

Instant Talk consists of three parts: the IPMM system, which can be reused in fu- ture applications, the Instant Talk Applica- tion Server, and the handset client. Instant Talk is fully compliant with PoC specifica- tions, which ensures interoperability and fa- cilitates rapid uptake of service.

REFERENCES

1	Heino Hameleers and Christer Johansson,	3	Gonzalo Camarillo, ÒSIP demystified,Ó	5 Jan Christoffersson, Hans Hannu, Stefan
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	14-27, 2002.		fersson and Lajos Zaccomer, "Improving	SIP/SDP compression," Proceedings of RVK
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	Peck, "The future of communication using		operations," Proceedings of VTC Fall 2003,	02, Stockholm, June 2002.
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Ericsson Review No. 1, 2004