VoIP Gateway TAU-4M.IP

Key features
  • Triple Play
  • VLAN per service
  • Autoprovision (TR-069, DHCP)

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Documents and files
Physical parameters


Office terminal
TAU-4М.IP is an access gateway intended for connecting analogue telephone and facsimile sets to an IP network. The service is provided via a converge data transmission network, where different IP-PBX can be used.

Transmission of facsimile messages is implemented by means of audiocodec G.711 pass-through and according to T.38 protocol.

High-quality sound
High performance hardware platform support of all basic audio codecs used in VoIP- networks (G.711, G.723.1, G.726, G.729), echo elimination functions, silence detector, comfort noise generator, DTMF signal reception and generation, as well as traffic prioritization mechanism (QoS) provide high quality of voice data.

In case of a primary SSW connection loss, the device switches to a redundant SSW and monitors the state of the primary one. If the device loses connection with both IP servers, calls between local subscribers still can be switched.


  • FXS ports - 4
  • WAN 10/100BASE-T port- 1
  • LAN 10/100BASE-T port for TAU-2M.IP - 1
  • USB 2.0 port - 1

VoIP protocols
  • SIP

Voice codecs
  • G.711 a-law, µ-law
  • G.722
  • G.723.1
  • G.726
  • G.729 (A/B)

  • T.38 UDP Real-Time Fax
  • a-law, µ-law G.711 pass-through

Voice standards
  • VAD (Voice Activity Detection)
  • CNG (Comfort Noise Generation)
  • AEC (echo cancellation, G.165, G.168 recommendations)

  • DTMF signals detection and generation
  • Transmission via INBAND, RFC 2833, SIP INFO

Value Added Services
  • Call Hold
  • Call Transfer
  • Notice of new call arrival (Call Waiting)
  • Call forward on busy (CFB)
  • Call Forward No Reply (CFNR)
  • Call Forward Unconditionally (CFU)
  • Caller ID
  • Calling line identification restriction (CLIR)
  • Hotline/Warmline
  • Call Group
  • 3-Way conference

VoIP functionality
  • Internal connections switching
  • Operating without SIP-server
  • Flexible numbering plan
  • Parameters profiles for ports
  • Settings are applied without rebooting
  • IMS (3GPP TS 24.623) support for Hold, CW, 3-Way conference, Hotline services management
  • SIP TLS support
  • # symbol transmission as %23

Quality of Service (QoS)
  • Diffserv and 802.1р priority assignment for SIP and RTP
  • Traffic prioritization according DSCP and 802.1p

Types of connections
  • Static IP address
  • DHCP-client
  • PPPoE
  • PPTP
  • L2TP

Network Functions
  • Bridge and router mode
  • NAT
  • Static routing
  • VLAN per service (Internet, VoIP, IPTV)
  • IGMP
  • DHCP, DNS server on LAN
  • Port forwarding
  • Firewall
  • 3G/4G-router mode
  • UPnP

Supported specifications
  • RFC 3261 SIP 2.0
  • RFC 3262 SIP PRACK
  • RFC 4566 Session Description Protocol (SDP)
  • RFC 3263 Locating SIP servers for DNS lookup SRV and A records
  • RFC 3264 SDP Offer/Answer Model
  • RFC 3311 SIP Update
  • RFC 3515 SIP REFER
  • RFC 3891 SIP Replaces Header
  • RFC 3892 SIP Referred-By Mechanism
  • RFC 4028 SIP Session Timer
  • RFC 2976 SIP INFO Method
  • RFC 2833 RTP Payload for DTMF Digits, Flash event
  • RFC 3108 Attributes ecan and silenceSupp in SDP
  • RFC 4579 SIP Call Control - Conferencing for User Agents
  • RFC 3361 DHCP Option 120
  • RFC 3550 RTP A Transport Protocol for Real-Time Applications
  • RFC 3611 RTP Control Protocol Extended Reports (RTCP XR)

  • WEB (English and Russian versions)
  • Telnet
  • FTP
  • Syslog
  • SSH
  • TR-069 (recommended to work with Eltex.ACS server)
  • DHCP autoprovisioning (periodically and scheduled)
  • SNMP (configuration and monitoring)

  • Username and password verification
  • Firewall
  • Access rights delimitation admin/user/viewer

  • USB-drive connection with FAT/FAT32/EXT2/EXT3/NTFS file systems
  • USB 3G/4G modem connection - operating in 3G/4G router mode

Main technical features
  • SDRAM 128 MB
  • SPI Flash 8 MB
  • OS Linux

  • Debug information output to Syslog/Telnet
  • Device status monitoring via Web interface
  • Subscriber lines parameters testing

Documents and files


Regardless of the operational lifetime stage, Eltex provides a 12 months warranty on all its telecommunication equipment.

During the warranty period the manufacturer ensures technical support and free-of-charge repair at the Enterprise which is situated in Novosibirsk.

As part of the warranty service, technical support is provided on the first-in first-out principle.

The priority support packages of 8/5 and 27/7 types are subjects to additional charges.

Physical parameters

Power adapter
  • 12V DC, 1 A
Power consumption
  • no more than 12.5 W
Operating temperature
  • from +5 °С to +40 °С
Relative humidity
  • up to 80%
Dimensions, mm
  • 187х120х32.5