Tel2 provides Asterisk SIP trunks and IAX2 trunking, FreePBX, and other open-source PBX platforms. We specialise in reliable connectivity, low-latency routing, and expert-level support for businesses and developers running their own telephony infrastructure.
As an Asterisk-focused VoIP provider, we offer deep protocol support, including IAX2, SIP (PJSIP and chan_sip), and advanced debugging assistance. Whether you're deploying a new system or troubleshooting an existing setup, our team works alongside you to keep everything running smoothly.
From simple SIP trunking to complex multi-site deployments, Tel2 is built for engineers who need flexibility, transparency, and control.
We provide Asterisk SIP trunks across the UK, supporting both small deployments and large-scale VoIP platforms.
Asterisk SIP & IAX2 Trunking Support
IAX2 Protocol Support
Tel2 supports Asterisk's IAX2 protocol which has a number of advantages over SIP:
- Efficiency: IAX2 trunking often uses less than half the bandwidth of SIP for multiple calls with the same codec.
- Simplicity: A single port handles both signaling and media, easing firewall traversal and reducing audio issues.
- DTMF Reliability: Always out-of-band, eliminating confusion over DTMF methods.
Media Support
We support all the main Asterisk codecs and media protocols including:
- Codecs: G.722, iLBC, G.729a, GSM, G.726, G.711 alaw and ulaw
- Video: H.264 and H.263 video codec support
- Fax: T.38 and UDPTL support
- Presence: SIP Subscribe for Presence and BLF
- MWI: OPTIONS and NOTIFY Support.
- Encryption: TLS and Secure RTP support for encrypted media
Technical Support
Tel2 understands and supports Asterisk at a deeper level than most UK VoIP providers. Here are some of the ways we can help you:
- Wireshark Captures: To identify faults
- Logging: Both IAX2 and SIP protocol and console debug logging to identify issues.
- Fraud Detection: Fraud management systems to protect customers
- Partner Program: Access to our Partners Programme
For full details, see our SIP Trunking services or explore UK and international phone numbers.