Displaying a non-TTNC CLI

It is possible to display a non-TTNC Number CLI on your SIP Trunk. There are, however, regulations in place to ensure that the number you're presenting is one that is allocated to you and is allowed to be used for this purpose.

TTNC allows you to pass on a Caller Line Identity (CLI) number which we pass out onto the UK and international PSTN telephone networks.

To restrict fraud and nuisance calls occurring, only 01/02 Local Numbers, 03 UK Wide Numbers and 0800/0808 Freephone Numbers can be used as an outbound CLI.

We don't allow the use of 070, 084, 087 or 09 Numbers under any circumstances.


This feature will be enabled on your account after you've signed and returned the CLI Customer Agreement document to agree with the following:

You will only pass CLI to us that is known to be true by you and allocated to the subscriber making the call, this can be achieved by three means:

  • The CLI value is assigned by your equipment to the call and overrides any number sent by the user. The value assigned is a telephone number that has been issued by us to you, or you have written proof from the network operator for that number range concerned that it has been allocated to the user or you.
  • The CLI value has been obtained directly from a recognised PSTN network operator via a TDM connection using ISDN / SS7 signalling.
  • The CLI value has been passed to you by us.

Using your CLI

Once the number has been added to your account, it can be selected as your default outbound display number from within myTTNC.

The registered number can also be passed from your PBX, which would override your default display number, and will be displayed as the CLI. If you attempt to pass a number which isn't registered to your account, the default outbound number will be displayed.


See the TTNC Website for more information.
The CLI Customer Agreement Form can be accessed here.

Updated 6 months ago

Displaying a non-TTNC CLI


It is possible to display a non-TTNC Number CLI on your SIP Trunk. There are, however, regulations in place to ensure that the number you're presenting is one that is allocated to you and is allowed to be used for this purpose.

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