Digital Module SFP-E1 for Asterisk

Digital telephone module SFP-E1 with echo cancellation (30 voice channels)


  • Legacy PBX, IVR Services, Asterisk IP-PBX
  • VoIP Gateways (supports SIP, H.323 and IAX)
  • SyncPPP, Frame Relay, Cisco HDLC, Multi-link PPP
  • a-Law, μ-Law, and Linear Modes Supported
  • Line coding HDB3, AMI


Terratel SFP-E1 module is designed to integrate and connect IP-PBX, IVR systems, VoIP-gateways, other specialized solutions of the Asterisk project or FreeSwitch to office PBXs, as well as the public telephone network PSTN via the E1 interface.

SFP-E1 is an optical module with an SFP form factor (Small Form-factor Pluggable) and support for Ethernet and E1 interface connections.

Digital SFP-E1 module for Asterisk network diagram

Pic 1. Block diagram of the inclusion of a Digital SFP-E1 module for Asterisk.

Digital SFP-E1 module is designed to build digital telephony systems based on Asterisk IP-PBX and exchanges data/voice over E1 channels.

Distinctive features

New SFP-E1 module is the latest addition to the D-201E/D-401E digital phone card family for the Asterisk project.

SFP-E1 module design uses unique technologies to support the E1/PRI environment. The SFP-E1 module is designed to connect traditional TDM systems with voice over IP technologies in a single network.

SFP-E1 module is installed in the sfp-slot of network equipment, which allows it to be used in any place where the network is available, and not just at the location of the Asterisk server.

SFP-E1 digital module is compatible with the Asterisk system through the DAHDI interface and can support the following protocols:

  • ISDN PRI (Lib PRI)
  • SS7 (Lib SS7)
  • R2 MFC (Lib OpenR2)

SFP-E1 digital module is compatible with all Asterisk versions and connects to Asterisk using a special DAHDI-enabled driver. A special driver with DAHDI support is available for free on the website.

SFP-E1 module has a hardware echo cancellation function for all voice channels of the E1 stream.

SFP-E1 digital module has the ability to configure via the web interface. follow>>

Key Features

  • Up to 30 simultaneous calls per 1E1 port
  • Supports E1 physical interface connections
  • TDM protocols support: ISDN PRI, SS7, R2 MFC
  • Industry standard RJ-45 port
  • SFP form factor

How to configure SFP-E1 Digital Module for Asterisk

The device is designed to emulation of time-division multiplexing (TDM) over a packet switched network (PSN).

For connection to IP-PBX Asterisk the DAHDI interface is used.

A simplified list of steps required to integrate an SFP device into an Asterisk system:

  • Download the driver assembly from our ftp server
  • Compile and download the driver module for your Linux kernel version
  • Generate a configuration file for the DAHDI system (dahdi_span_assignments dumpconfig> /etc/dahdi/assigned-spans.conf)
  • Configure Asterisk to use regular DAHDI channels
  • Configure SFP module
  • Restart the Asterisk server

Connecting SFP-E1 module via Ethernet media converter

If during the deployment of the SFP-E1 module for connecting communication systems based on the SIP protocol and devices using the E1 interface it is not possible to connect it to a local area network (LAN), you must use a budget media converter.

Connecting SFP-E1 module via Gigabite Ethernet Media Gateway

Pic 2. Sample of connecting SFP-E1 module via Ethernet media converter

These media converters are designed to convert the signal and then connect the 1000BASE-SX fiber optic cable with a 1000 Base-T twisted pair cable.

Digital Module SFP-E1 for Asterisk Technical Specifications

System Type
SFP module
Legacy PBX/IVR Services
Voice over Internet Protocol (VoIP) services
Complex IVR Trees
“Meet-Me” Bridge Conferencing
VoIP Gateways (supports SIP, H.323 and IAX)
Calling Card Platforms
Voice/Data Router
PRI Switch Compatibility – Network or CPE
Asterisk IP-PBX
Port Features
HDB3, AMI Line coding
CRC-4, not CRC-4, E1 Frame alignment
Data Transfer Protocols
Frame Relay
Cisco HDLC
Multi-link PPP
Voice Transfer Protocols
E&M Wink
a-Law and Linear Modes Supported
Hardware Requirements
SFP Slot
Software Requirements
Linux kernel 2.6.x