What Is SIP?

SIP (Session Initiation Protocol) is the signaling standard that starts, manages and ends internet phone calls. It tells phones and servers who is calling whom and how to connect them, while the voice itself travels separately. A SIP trunk is a virtual phone line that connects a business phone system to a carrier over the internet.

How it works in Salesforce

When an agent clicks to call in Salesforce, a chain of systems sets up the call:

1. The softphone asks the calling platform to start a call.
2. The platform uses SIP to signal the carrier, often over a SIP trunk.
3. The carrier connects to the customer's phone on the public phone network.

SIP also handles changes during the call, such as holds, transfers and conference calls, and signals when the call ends. Agents never see SIP directly, but it's why cloud calling can scale: adding capacity means adding SIP trunk channels rather than physical phone lines.

Teams that already have a carrier or phone system sometimes ask whether they can keep it. The answer depends on the CTI provider, so check which carriers and setups your provider supports.

Example

A contact center adds 20 seasonal agents. Instead of installing new phone lines, the IT team adds SIP trunk channels and the new agents start calling from Salesforce the same day.

How 360 CTI handles it

360 CTI runs cloud calling inside Salesforce. Talk to our team about the carriers and telephony setups in your region. See the Cloud Contact Center solution.

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