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| For an IMS service provider, it is very important to interwork with other IMS providers as many as possible. Based on that interworking capabilities, the IMS customers can get full advantage of communicating with other people or services. Currently, the 3GPP is standardizing BCF (Border Control Function) as a gateway for IMS networks. The BCF is composed of IBCF (Interconnect Border Control Function) and TrGW (Translation Gateway). The IBCF provides overall control of the boundary between different service provider networks. It provides security for the IMS core in terms of signaling information by maintaining security association with the peer and performing a signaling-based topology hiding function. It also performs IPv4-IPv6 interworking and session screening based upon source and destination signaling addresses. Lastly, the IBCF interacts with the TrGW for control of the boundary at the transport layers including pinhole firewall, NAPT (Network Address and Port Translations) and numerous other features. The TrGW controls the transport boundary at layers 3 and 4 between service provider networks. This function acts as a pinhole firewall and NAT device protecting the IMS core. It controls access by packet filtering on IP address/port and opening/closing gates into the networks. QoS packet marking, bandwidth policing, usage meting, and QoS measurements for the media flows are additional features supported by the TrGW.
Nable¡¯s IBCF/TrGW is fully compliant with 3GPP IMS standards and provides all of network border functions that are required for the interworking with other IMS networks.
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| Features |
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Topology hiding interwork gateway |
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Application level gateway |
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Screening of SIP signaling |
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Border control function |
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Transit routing function |
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Transport plane control function |
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IP version interworking - among IPv4 and IPv6 |
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Support Non-3GPP SIP profiles |
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Support GRUU |
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Support NAT traversal - Full cone. Symmetric, port-restricted cone types |
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Support of high performance media relay - RTP, RTCP, MSRP, XCAP |
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Support of various IMS services (VoIP call-voice, and video over call, IM, presence, etc.) |
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