Comparison of H.323 and SIP Currently, 3GPP uses SIP as a core protocol of the third generation mobile communication full IP network. The protocols built in Netmeeting in the WindowsXP operating system are also changed from H.323 to the SIP protocol, taking into account its business. Flexibility, the SIP protocol will become the direction of future development. Comparison of SIP and BICC BICC is proposed directly on the application of telephone services. From traditional telecom camps, it has a more rigorous architecture, so it can provide very good business to implement existing circuit exchange telephone networks in soft exchange. Transparency. In contrast, the SIP architecture is not perfect as BICC definitions, and SIP is mainly used to support multimedia and other new services, and have more flexible and convenient features based on multiple business applications based on IP networks. BICC is developed based on ISUP, which is more mature in voice service support, which can support all voice services, supplementary business and data services, but BICC protocols are complex and scalable. In wireless 3G applications, the BICC protocol is at the NC interface of the 3GPPR4 circuit domain core network, providing support for call continues between (g) MSCServer. In fixed network soft exchange applications, the BICC protocol is in a hierarchical architecture, providing support for call connection between different soft exchanges. When using a BICC architecture, you can keep all the current functions, such as numbers and routing, etc., still use routing concepts. This means that the management method of the network is very similar to the existing circuit switched network. Conversely, there is no BICC mature in terms of voice services, but it supports strong multimedia services, good scalability, and can be expanded according to different applications. In fixed network soft exchange applications, the SIP protocol is at the call control layer in the flat architecture, providing support for call connection between different softswitch. When using the SIP architecture, there are two cases from a routing perspective: the first case, the normal ISUP message adds some information to the SIP message to transmit, call the server, number, routing analysis and signaling and the interworking of the business. The function remains unchanged, and the routing analysis guides to the addressing of the target IP address. The second case is based on the Enum (IETF's Phone Number Mapping Working Group) database. In this manner, the call control of the call server is completely different from the call control in the existing circuit switched network, and there will be no number and routing analysis in the call control, but business mapping and interoperability are still required. Since the circuit identification code CIC, ISUP management process, message delivery protocol MTP, the standard ISUP protocol should be modified accordingly. The management of the network has been simplified to some extent (if you do not need to build a signaling network, there is no routing definition). In addition, compared with existing networks, operators have changed huge changes in the control of the network and the control mode. Through the above analysis, the SIP protocol will be used to some extent, and the functions in some existing telephone networks are lost to some extent. To introduce these features, you need to expand the SIP protocol. In comparison, BICC can basically provide all existing telephone networks. It is believed that the modified and standardized SIP can reach the support capabilities of BICC on legacy services. Comparison of SIP-T and SIP-I About Softswitch SIP Domain and Traditional PSTN There are currently two standard systems, namely IETF's SIP-T protocol and ITU-T SIP-I protocol. 1. ITF's SIP-T Protocol SIP-T (Sipfor Telephones) is defined by the RFC3372 of the ITFMMusic workgroup, including RFC3372, RFC2976, RFC3204, RFC3398, and the like. It uses end-to-end research methods to establish three interworking models when SIP and ISUP interoperability, namely: Calls initiated by the PSTN user by the SIP network by the PSTN user; the call is initiated by the PSTN user; call by the PSTN user The SIP user is terminated. SIP-T is the interoperability of SIP and ISUP, namely package, and mapping, which are defined by RFC 3204 and RFC3398, respectively. However, SIP-T only focuses on the interoperability of basic calls, and it is basically not involved in supplemental traffic. 2. ITU-T SIP-I Protocol SIP-I (SipwithenCapsu) protocol includes TRQ.2815 and Q.1912.5 of ITU-TSG11 working group. The former defines the technical needs of SIP and BICC / ISUP, including intercom interface models, and the interactive unit IWU should support the protocol capacity set, and the security model of the intercom interface. The latter definpends the interworking of 3GPPSIP and BICC / ISUP based on the different protocol power configuration sets required on the NNI on the NNI on the SIP side, in general, interoperability of SIP and BICC / ISUP, SIP with ISUP message package ( SIP-I) Interoperability with BICC / ISUP. The SIP-I protocol reuses many IETF standards and drafts, but not only the interworking of basic calls, but also the interoperability of BICC / ISUP supplementary business. 3. The SIP-T and SIP-I is obvious, the content of the SIP-I protocol is far from the content of SIP-T. The SIP-I protocol family not only includes the interworking of basic calls, but also interoperability of CLIP, CLIR, etc. In addition to the interoperability of call signaling, it also takes into account the resource reservation, media information, etc .; Interoperability of SIP and BICC / ISUP in a soft exchange environment, also interoperable 3GPPSIP and BICC / ISUP, and so on. It is especially important that the SIP-I protocol family has an inherent clear and accurate specific and detailed specificity of the ITU-T standard, which is operative. And 3GPP has employed Q.1912.5 as the ultimate standard of IMS and PSTN / PLMN. Therefore, the interoperability of softswitch SIP fields and PSTN should follow the ITU-T SIP-I protocol. In fact, many telecom operators have finally selected SIP-I to abandon SIP-T. Based on the above comparisons and analysis, we can draw the following conclusions: In the interoperability agreement between soft exchanges, the application is SIP-T. The mobile application is BICC. The future development direction is SIP-I; In terms of control protocols between soft exchange and media gateways, MGCP is more mature, but H.248 inherits all the advantages of MGCP, with the trend of replacing MGCP; the control protocol between soft exchange and IAD, MGCP is more mature, However, H.248 inherits all the advantages of MGCP, replacing MGCP trends; SIP is trend; SIP is a mainstream between soft exchange and application servers, and SIP is currently based on this business interface. Mature; application server and third party business, Parlay is the direction, but the current commercial is immature. Technology area
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