ISDN PRI VoIP Gateway

Overview

ISDN PRI VoIP gateway is designed for the effective integration of office, office and terminal exchanges, as well as other telecommunication TDM equipment supporting PRI interface in IMS and NGN networks.

To manage PRI interface channels, the device fully implements support for Euro ISDN, DSS1, QSIG, Q.931 signaling protocols.

The PRI VoIP gateway supports call routing in any order: TDM-SIP, SIP-TDM, TDM-TDM and SIP-SIP.

Additional functionality is the conversion of the PRI interface into the SS7 signaling system, which will enable the office PBX to be included in the local switching unit.

ISDN PRI VoIP Gateway is an optional product of the Terratel SIP/E1 Media Gateway model.

Functionality

The gateway has the following important functional features:

• Support for telephone signaling protocols of the PRI interface – DSS1, Q.931 or QSIG
• Up to 16 E1 PRI interfaces that can be configured for TE Terminal Equipment or NT Network Terminal mode
• Support for built-in IP-PBX functions
• Simultaneous support of SS7, V5.2, R2 MFC, R1.5 signaling in one device
• Possibility of combining several telephone exchanges into a corporate network with internal numbering
• Ability to implement IP-TDM-IP, TDM-TDM and IP-IP connections
• Redundant AC or DC power supply
• Ability to reserve communication using E1 bypass

PRI interface configuration

For DSS1 signaling (QSIG or Q.931 protocols), in addition to setting the parameters common to all signaling, it is necessary to select the appropriate value for the parameter “Interface type for ISDN PRI”: “TE: user” or “NT: network”.

Digital Signalling System DSS1 for PRI interface

ISDN (Integrated Services Digital Network) is a service-integrated digital network that combines voice, data, and image communications.

For corporate and operator TDM equipment, the ISDN standard mainly uses the Primary Rate Interface (PRI).

The joint operation of digital telephone exchanges connected via the PRI interface is provided by the DSS-1 signaling system or the QSIG (Q-Point Signaling System) symmetric protocol based on ITU-T Q.931 recommendations.

DSS1 (digital subscriber signaling #1) is an ISDN digital subscriber signaling protocol developed and standardized by ITU-T for the primary PRI access interface. This protocol transmits signaling messages through the User-Network interface via the D-channel of this interface.

The Primary Rate Interface (PRI) combines 30 V-channels for voice or data, one D-channel for signaling and one H-channel for overhead data of standard E1 2.048 Mb / s (30B + D + H).

Modifications of DSS1 or its other names are possible: EDSS1, Euro DSS1, Euro-ISDN, ISDN PRI, NET5 for PRI, Q.931, symmetric signaling protocol QSIG.

PRI PBX Integration with SoftSwitch

To upgrade telephone networks using ISDN PRI or DSS1 signaling, the introduction of a specialized VoIP gateway is proposed.

The first option arises when you need to replace the digital TDM switch with the SoftSwitch software switch. If a number of subscriber extensions was connected to the TDM switch via the PRI interface, then they can be switched to SoftSwitch using the VoIP gateway as shown in the pic.

In this case, the PRI/DSS1 signaling of the subscriber concentrator is connected to the VoIP gateway, which in turn is connected to SoftSwitch via the SIP protocol data network.

Integration of SIP subscribers through PRI signaling

The second option occurs when it is necessary to connect SIP-subscribers of the local network to the numbering capacity of PSTN (public switched telephone network). For example, a telecom operator already has a digital TDM switch with free PRI interfaces. In this case, the VoIP gateway towards the TDM network looks like a subscriber extension PRI, and towards the IP network like an IP-PBX on which SIP subscribers are registered (see pic).

 

PRI Signaling Conversion Option

Support in one signaling device ISDN PRI, DSS1, QSIG, Q.931 and SS7, the main PSTN network signaling system, allows you to use a VoIP gateway as a signaling and protocol converter.

This is important when a telecom operator reconstructs TDM networks when there is a need to adapt various telecommunications equipment to PRI signaling.

Terratel PRI VoIP Gateway can be used in a variety of IP and PSTN interfaces to minimize costs and reduce operating costs.

Technical Specifications

Network Interfaces
TDM	up to 16 E1 interfaces
SIP and RTP	up to 480 VoIP channels, 10/100/1000 BASE-T Ethernet
Management	Fast Ethernet, RS-232

Signaling Protocols
IP	SIP, RTP, RTCP, TCP, UDP
PSTN	SS7, ISDN PRI (DSS1, QSIG, Q.931), V5.2, V5.1, R2 MFC, CAS

Feature Support
Voice codecs	G.711 (a-law, µ-law), G.723.1, G.726, G.729a/b
Voice processing	Adaptative programmable jitter buffer, VAD, SID, CNG
DTMF	RFC2833, SIP INFO, RFC 2976
FAX	fax over G.711, T.38 fax relay
Echo Cancellation	G.168 up to 128 ms
Registration and Authentication	up to 10000 SIP-subscribers
Registration	SIP-trunks
Call Routing	TDM-SIP, SIP-TDM, TDM-TDM and SIP-SIP

Power
	Single/Dual-redundant 220 VAC or/and 48/60 VDC Input
	Up to 28W Power consumption (for 16 E1)

Operations Management
	GUI via Embedded Web Server
	SNMPv2 monitoring
	Syslog Telnet (for CLI)

Security
	Integrated firewall, Password protected access, SSH, RADIUS login

Operating Environment
Operating temperature	from 0°С to +60°СHumidity
Humidity	up to 80% at +25°С

Hardware
System Type	Board
Dimensions	1U high, 19″ wide rack mountable

Delivery Set

SIP/E1 Gateway Lite:

• SIP/E1 Gateway Lite (1Е1, 30 SIP channels, G.711, T38 codecs, echo cancellation G.168)

SIP/E1 Gateway:

• SIP/E1 Gateway (2Е1, 240 SIP channels, G.711, G.726, G.729, T38 codecs, echo cancellation G.168)
• SIP/E1 Gateway (4Е1, 240 SIP channels, G.711, G.726, G.729, T38 codecs, echo cancellation G.168)
• SIP/E1 Gateway (8Е1, 240 SIP channels, G.711, G.726, G.729, T38 codecs, echo cancellation G.168)
• SIP/E1 Gateway (12Е1, 240 SIP channels, G.711, G.726, G.729, T38 codecs, echo cancellation G.168)
• SIP/E1 Gateway (16Е1, 480 SIP channels, G.711, G.726, G.729, T38 codecs, echo cancellation G.168)