Outbound trunking is a feature that allows you to present other direct dial-in (DDI) numbers as Caller ID on your registered trunk relieving phone administrators the onerous task of individually registering large blocks of numbers to preserve CLI.
The Problem Outbound Trunking Resolves
Using Registration (i.e. not Peering) – system administrators can only present the registered number as the Caller ID which quickly becomes unmanageable for phone administrators managing large number blocks.
Setup outbound trunking
With SIP a Caller ID is made up of 2 parts, the name and number, for example for phone number 442034567890:
After you’ve enabled outbound trunking you can present another number on the account as your Caller ID using the name part of the Caller ID field. In the example below we are presenting the CLI 442034567891 on the registered line 442034567890:
- Log into https://now.tel2.co.uk
- Select CloudPBX | Outbound Calls | Select Number >> Outbound Trunking
- Click Enable outbound trunking on the line you wish to configure as the accounts Outbound Trunk DID.
- Click Save settings to update.
- Display name: Most devices such as soft phones and IP Phones refer to the name part as the Display name.
- Asterisk based PBX systems the name part can be set in the SIP or IAX2 configuration with the callerid= field – or if you wish to present it in the dial plan then you use the CALLERID (name) variable. By changing this name part to the number you wish to present on the call you can achieve multiple caller ID presentations for each DDI over a single registration or login.
- P-Asserted-Identity: see also a P-Asserted-Identity header (RFC 3325) to define the Caller ID as an alternate to manipulating the name field (subject to your system support for RFC 3325).