The TTNC SIP Trunk service provides an IP connection between our network and your PBX over the Internet. This gives your PBX access to the public switched telephone network (PSTN) allowing you to make and receive calls
You can create SIP Trunks instantly and manage them in the cloud via our platform, myTTNC. This will give you dynamic call capacity, improved resilience and access to a wide range of hosted call management services.
We support connections ranging from two channels for small PBX equipped businesses, to an unlimited amount of channels for call centres and enterprise customers.
Scale and provision instantly
Provision numbers and services instantly. Scale your call capacity at anytime by adding or taking away the number of channels you use
Advanced SIP Trunk management
Create user credentials and ACLs for SIP Registration and Static IPs. Mix PBX endpoints and standalone IP phones using SIP registration
CLI and Number flexibility
Manage your CLI presentation and numbers for outbound calls. Choose from over 7 million UK numbers or migrate your existing number to us
Benefit from free calls between offices and workers using our SIP Trunking service, a reduction of ISDN line rental and lower ongoing call charges
Reliable business continuity
Our SIP Trunking provides better business continuity than ISDN and includes disaster recovery (DR) and automatic failover features as standard
Integrated Hosted Telephony
Combine SIP Trunking with our advanced hosted telephony services such as Call Recording, Voicemail, IVR menus and Call Management services
What do you need and how does it work?
You'll need an IP enabled PBX, a TTNC phone number and an Internet connection.
- After adding a SIP Trunk to your account, you need to configure it in the myTTNC portal.
- This is when you assign the outbound Caller ID and set up the authentication method for your PBX. It's a straightforward process and shouldn't take longer than one or two minutes.
- Once the SIP Trunk has been configured and set up on your PBX, you can forward any of your TTNC phone numbers to the SIP Trunk. We also provide automatic failover to PSTN, so you can choose to have incoming calls automatically forwarded to another destination (PBX, landline or mobile) if your PBX loses its Internet connection.
- You can change the Caller ID whenever you want and use any of the numbers in your account. You can even present your own number (once we’ve verified it).
Please note: A TTNC number is still required when displaying a registered CLI.
Why use TTNC?
- Providing VoIP services for more than 15 years
- 16,000 businesses already use our services
- Range holder of over 7 million phone numbers
- UK owned and operated with 24/7 support
- Multi-Award-Winning VoIP service
- ITSPA member and regulated by Ofcom
- Holders of the ITSPA Quality Mark
- Ofcom approved Code of Practice
SIP Trunk Pricing
|SIP Trunk (including 2 inbound channels)||Cost|
|Additional inbound channel||£2|
Inbound Call Charges
|Inbound Number / Pay As You Go (PAYG)||Rate|
|01, 02, 03 and 070 Numbers ||0p/min|
|084 Service Numbers||0p/min|
|0800 and 0808 Freephone Numbers||2p/min*|
* Price is for calls originating from UK landline; add 2.5p/min for calls originating from UK mobiles.
Outbound Call Charges
Pay As You Go (PAYG) is great if your call volumes are lower or unknown. Pay Monthly is ideal for those who spend a lot of time on the phone and want our lowest call rates.
Pay As You Go (PAYG)
|Top up Amounts||Calling to a UK Landline||Calling to a UK Mobile|
|£10, £25, £50||1.5p/min||5.5p/min|
Top up call credit on your account only when you need to.
|Tariffs||Calling to a UK Landline
(UK Landline minutes)
|Calling to a UK Mobile
(UK Mobile minutes)
|£10 per month||680
|£15 per month||1,080
|£25 per month||1,950
|£45 per month||3,800
|£60 per month||5,500
Adds call credit to your account on the 1st of each month.
The rates shown are per minute and based on calling a UK destination. A minimum cost of 1p applies to each chargeable call.
For all other destinations, please download our rate sheet.Download Rate Sheet
SIP Trunks FAQ's
What do I need to get started?
An Internet connection (3G, 4G, broadband)
A Virtual Number from TTNC
An IP PBX
How much bandwidth do I need?
On average, 3 concurrent calls would take about 256kbs of bandwidth when using the G.711a Codec, which is a high quality Codec TTNC uses
What Codec does TTNC use?
TTNC uses the G.711a Codec, which is one of the highest quality Codecs available. It provides digital quality and sound quality is superior to analog.
What is a Codec?
Codec stands for Coder-decoder. It converts an audio signal (your voice) into a compressed digital format for transmission (VoIP) and then back into an uncompressed audio signal for replay.
Codecs vary in the sound quality and the bandwidth required, most softphones, IP phones, IP PBX’s and Gateways supports several different Codecs.
What kind of Internet connection do I need?
A standard broadband connection is sufficient to surf the Internet and use for voice calls at the same time.
What is call quality like?
Assuming you have a good Internet connection, call quality will be superior or the same as you receive when you use a landline or mobile phone.
Do SIP Trunks have a contract or set up charge?
No, there's no set up charge or contract to sign.
Can SIP Trunking replace ISDN lines?
Yes. SIP trunking provides a highly flexible alternative to ISDN and and is also more cost effective than ISDN.
How do SIP Trunks work?
SIP Trunks connect your PBX to TTNC's network, enabling full PSTN conectivity.
Connection from your PBX to our network is via an IP connection, such as broadband or Ethernet, and is delivered as an end-to-end service. There's no outbound channel limit and you can add inbound channels in real time via myTTNC.
What are SIP Trunks?
SIP Trunks (or SIP Trunking or VoIP Trunks) enable you to use an Internet connection to make and receive calls.
Ordering and adding SIP Trunks
If you already have an account with TTNC and want to make use of this service from today, you can simply add this, along with any of our other services, at any time through the store in myTTNC.
Otherwise, click the button below and you'll be up and running in minutes.