Introduction to Voice Gateway

--> Voice Gateway is a component in VOIP solution used to connect IP Network with the PSTN Network.

--> The Voice Gateways are used for forwarding calls when the internal IP Phone has to communicate with the PSTN and private branch exchanges (PBXs), analog phones, fax machines, and modems.

--> Voice Gateway must be integrated with Cisco Unified Communication Manager.

--> Trunk interfaces are used to provide communication between Voice Gateway and PSTN.

--> Voice Gateway signaling protocols are used to provide communication between Voice Gateway and Cisco Unified Communication Manager.

--> Voice Gateway signaling protocols are also called as Gateway Protocols.

--> Voice Signalling Protocols does not transport voice stream, it simply selects the signaling path on which voice traffic needed to be forwarded.

--> RTP/RTCP are used to forward audio stream between the endpoints.

--> There are four signaling protocols are used to provide communication between Voice Gateway and Cisco Unified Communication Manager.

i) H.323

ii) SIP

iii) SCCP

iv) MGCP

--> Selection of Particular voice signaling protocol between Voice Gateway and CUCM depends upon various criteria, such as

i) Whether the VOIP network is totally Cisco or Mixed Vendor network.

ii) Type of Voice Architecture used in VOIP Network ( Distributed or Centralized).

--> Voice Gateways are also performed in translation between two different voice codecs using DSP.

Ref: Cisco.com