SIP Trunking

Connect your existing phone system to SIPcity using SIP trunks.

Trunking is a registration feature that allows PBX administrators to present the Caller ID (CLI) of different numbers via a single registered Trunking number. It’s useful for on-premises IP-PBXs that don’t support SIP Peering and require registration credentials instead.

Set up Trunking

  1. Select Switchboard > your number.

  2. Select Preferences > Trunking.

  3. Set your Inbound Trunking Pilot Number.

  4. Click Save.

Trunking options

  • Inbound Trunking: Routes all numbers to a single registered number. Useful for on-premises PBXs that don’t support static IP peering.

  • Outbound Trunking: Allows you to present different Caller IDs on your account through a single Trunking number, avoiding the need to register each number individually.

Trunking configuration

Additional notes

  • Display name: Softphones and IP phones display the name part of the SIP URI.

  • P-Asserted-Identity: Use the P-Asserted-Identity header (RFC 3325) to define Caller ID as an alternative to the display name field (requires system support for RFC 3325).

  • Groups: All From numbers must belong to the same group as the Outbound Trunking number.