Overview
An IMG can perform a two-way conversion between circuit-switched data (TDM) and packet-switched data (VoIP). A conversion is required if going from circuit switched data (TDM) to packetized voice applications such as the Voice over Internet Protocol (VoIP). Circuit-switched voice is converted to IP packets using compression algorithms that can increase capacity toward the IP network side. An IMG can also integrate media resources over IP technology. One of the benefits offered by the IMG is that it supports modifying the parameters of an individual call while the call is active. This enables capabilities such as being able to change the quality of service without losing a call.
Integrated Media Resources
Typically media resources are connected by T1, E1, or J1 interfaces that consume one 64 Kbps port per call. This can limit the capacity of the system. An IMG integrates media resources over IP using the standards-based Real-Time Protocol (RTP).
Integrating media resources using standards-based technology allows media resources to be shared between an IMG and other network infrastructure. Packet switching to media resources allows the application to benefit from voice compression and increased capacity on the application. This flexibility allows an IMG and the applications to scale independently and incrementally as needed, which in turn can eliminate excess hardware.
Summary of IMG VoIP Features
Supports SIP RFC 3261
Supports SIP RFC 3581
Supports H.323 V2
Supports up to 512 VoIP resources. (Depending on configuration)
Supports IP Bearer Profiles with multiple IP Profile entries (7 per IP Bearer Profile)
Supports Integrated Media Resources
Supports the following codecs as listed in
Supports Q.1912.5 Support for SIP --> ISUP
Supports having Vocoder Data in the CDR of the Radius message
Supports Reason Headers in both TDM to SIP as well as SIP to TDM (RFC 3326)
Supports SIP Privacy for SS7 to SIP, SIP to SS7, ISDN to SIP, SIP to ISDN, SIP to SIP, and ANSI SS7 to SIP.
Supports Fax.
Supports G3 Fax Relay that is compliant with the T.38 ASN.1 standard Group 32.4 – 14.4 kbps, T.38 compliant fax relay or switch to PCM (synchronized with SIP or H.323).
Supports Modems up to V.92 rates, automatic switch to PCM
Supports switching between Voice/Fax/Data and is synchronized with SIP or H.323
Supports Echo Cancellation
G.168-2000 Compliant; Maximum tail:
VoIP Module SLM-IPM-1001R - 128 milliseconds (Mindspeed Modules)
VoIP Module SLM-IPM-0001 - 64 milliseconds. (Older BroadCom Modules)
Supports Ping Capabilities
Supports Jitter Buffer
Supports Symmetric NAT Traversal. See the following link: IMG 1010 - Symmetric NAT Traversal
Supports Transcoding between IP network codecs. See the following link: IMG 1010 - Transcoding
Supports RFC 4040 (RTP Payload Format for a 64 kbit/s Transparent Call)