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VoIP Gateways | SIP Gateways: What is a Voice Gateway?

Voice-over-Internet-Protocol is a packet-based technology for transmitting digitized voice over an Ethernet/IP network. Because many businesses deliver the packetized voice traffic across the Internet to lower the phone bill, VoIP is sometimes called Internet Telephony. VoIP technology, or packet-based voice, underlies such recent developments as unified communication (UC). Related terms include network transformation--referring to carriers that migrate to All-IP network service delivery--as well as real-time communication, since voice transmission is especially sensitive to network issues as delay and jitter (variance in delay).

A VoIP gateway--a.k.a. analog telephone adapter (ATA)--is a networking device that converts a traditional (legacy) phone signal (analog or digital) into a (digitized) packet-based, Internet Protocol (IP) communication stream. The gateway serves as the conversion point between Time Division Multiplexed (TDM) telephone network and an IP-based network such as the Internet or private corporate LAN or WAN.

Traditional business-class telephony services include PRI, E1 and T1 trunks, plain old telephone service (POTS) interfaces like FXS and FXO (learn more about FXS/FXO technology) as well as BRI and PRI interfaces for integrated services digital network (ISDN). (Glossary of telecom terms.) The gateway converts voice received from the PBX into IP packets suitable for transmission over a data network. Similarly, the gateway re-formats the stream of incoming IP data packets for use by the PBX system.

What is another name for a VoIP Gateway?
A VoIP gateway may be referred to by many other names, such as SIP gateway, FXS gateway, FXO gateway, or analog telephone adapter. For more answers to the question "What is another name for a VoIP Gateway?" see the list of synonyms at the bottom of this page...

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T1/E1/PRI ISDN Gateway

SmartNode 4170 - T1/E1/PRI ISDN Voice Gateway
SmartNode 4170
Transport your enterprise phone system to the world of IP Telephony with the SN4170 T1/E1/PRI Gateway. Supports up to 30 concurrent G.711/ G.722 voice/fax calls with secure HTTPS, stateful firewall, and TLS/SRTP.

Analog Gateway with 2, 4 or 8 FXS/FXO ports

SmartNode 4110 - Analog Gateway with 2-8 FXS/FXO ports
SmartNode 4140
The SmartNode 4140 Series of VoIP Analog Gateway products support up to eight telephone connections integrating legacy equipment into a UCC environment. High-quality voice and reliable fax over any IP network. All-IP does not end when analog terminals have to be integrated. Security and quality guaranteed.

SS7 TDM-to-IP Media Gateway with T1/E1/J1

SmartNode 10100 - SS7 TDM-to-IP Media Voice Gateway with T1/E1/J1
SmartNode 10100
The carrier-grade SmartNode 10100 SS7 gateway supports 128 to 256 calls. Smaller service providers can use this SS7 gateway to drive convergence between TDM and IP networks. The SN10100 carrier gateway replaces multiple devices for signaling, connectivity, and media transcoding.

ISDN-to-IP Gateway with 2, 4 or 8 BRI S0 ports

SmartNode 4130 - ISDN-to-IP SIP Gateways with 24 BRI S0 ports
SmartNode 4130
With up to 4 BRI ports and 8 simultaneous G.711 voice channels, the SN4130 is the best way to connect ISDN networks or ISDN terminal equipment to the world of voice over IP. It supports up to 5 G.711 or up to 8 G.722 voice/fax calls concurrently with secure HTTPS, stateful firewall, and TLS/SRTP.

Teach Me: VoIP Gateways, Voice Gateway Tutorial: How can you use VoIP Gateways or SIP Gateways?

A VoIP Gateway can support numerous use cases (application scenarios) to enable IP telephony implementations. A media gateway may provide several types of bi-directional conversion, including SIP-to-TDM and TDM-to-SIP. Some high-end models may even provide such session border controller (SBC) functions as transcoding, security firewall, failover, and others.

Typical Applications
VoIP media gateways can be used to address many different challenges when implementing an IP-based voice system. Three of the most common use cases are summarized below.

Legacy TDM-to-IP/SIP
PSTN (T1/E1/PRI) to All-IP Voice System
The primary driver for TDM-to-SIP deployment is known as "toll bypass" which reduces a company's operating costs by avoiding the expensive tolls levied by a public switched telephone network (PSTN). Instead of a Telco trunk, the SmartNode gateway connects a legacy business phone system to a much lower-cost SIP trunk, delivered by an Internet telephony service provider (ITSP).

Drawing shows a Voice Gateway interconnecting FXS phones and a FAX machine with enterprise IP LAN

VoIP Provider to Legacy PBX
ITSP or cloud/hosted/virtualized SIP trunking service to Analog POTS or Digital ISDN PBX.
A VoIP gateway can connect a state-of-the-art All-IP communications system (on-premise IP PBX or cloud/hosted/virtualized IP PBX) to a legacy PTSN trunk. You can upgrade a legacy business phone system using an IP media gateway so it can connect to an ITSP over a SIP trunk. SIP trunks are much less costly than expensive toll-based legacy T1 lines.

Drawing shows sip gateways in a hybrid VoIP migration SIP trunking application with IP PBX, IP phones and ISDN PBX and phones

Migration from Legacy to IP PBX
Going the other way round, in a SIP-to-TDM deployment, the gateway connects a modern SIP communications system with a T1/E1/PRI service provided by a legacy carrier. Keep the existing business phone system up-and-running while transitioning to a new IP based phone system.

Drawing shows VoIP migration sceanrio with dual SIP trunks and voice over IP gateways

VoIP Gateway Terminology
Short Glossary of Related Acronyms
VoIP - Voice over IP
SIP - Session Initiation Protocol
IP - Internet Protocol
TDM - Time Division Multiplexing
PRI - Primary Rate Interface
ISDN - Integrated Services Digital Network
PSTN - Public Switched Telephone Network
ITSP - Internet Telephony Service Provider
FXS - Foreign eXchange Subscriber interface
FXO - Foreign eXchange Office interface

Common Synonyms
IP Media gateway
SIP gateway
Voice gateway
TDM gateway
PSTN gateway
PRI gateway
ISDN gateway
Digital Telephony gateway
FXO Gateway
FXS Gateway
Enterprise Gateway
SME Gateway
Digital Telephony Gateway
Analog Telephone Adapter (ATA)


Help Me: Technical Technical help for VoIP Gateways, SIP gateways, and voice gateway implementations

Patton offers an extensive online library of technical information to help you get your SmartNode up and running in a jiffy. Patton's web-based FAQs, configuration notes, and application notes provide the detailed knowledge you need to install, configure, troubleshoot and maintain your SmartNode product. And these helpful resources are all free right here on patton.com. Patton stands behind our high-quality VoIP media-gateway products-world-renowned for set-it-forget-it reliability and stability-with live email and phone support plus lifetime downloadable software updates absolutely free of charge.
Sales: sales@patton.com / +1 301 975 1000
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