Choose Your Communication Protocol

You can use one of these protocols to route calls to an agent.

Public Switched Telephone Network (PSTN)

With PSTN, you use a permanent, fixed phone number to transfer incoming calls to your agent. Configure your partner contact center to claim this number and route calls to it.

• Regional availability: US and Canada only
• Call travels over: Phone network
• Call context passed to Salesforce: None. Salesforce identifies the org from the static number. See Connect Related Voice Calls When Using PSTN.
• Partner requirement: Any partner contact center

Choose PSTN if you're based in the US or Canada and want a simple setup that doesn't require partner-side API calls. Because PSTN relies on Caller ID, context linking isn't guaranteed for concurrent calls. For more reliable context linking, consider SIP or Dynamic Routing.

For details, see Configure the Channel and Telephony Settings for PSTN.

Session Initiation Protocol (SIP)

Your telephony partner sends calls directly to Salesforce over the internet, using a SIP trunk. The SIP message includes the call context in its header, eliminating the need for a Salesforce phone number. You configure your partner contact center to transfer inbound calls to the agent using this SIP address.

• Regional availability: Global
• Call travels over: Internet (IP)
• Call context passed to Salesforce: Full context via SIP headers. See Connect Related Voice Calls When Using SIP or Dynamic Routing.
• Partner requirement: Requires integration with a vetted partner. For a list of supported partners, see Agentforce Voice with SIP Regional Availability Chart.

Choose SIP for a direct, reliable connection with low call-setup latency. By routing calls over an encrypted IP connection (SIP-over-TLS), you bypass PSTN carriers, avoiding per-country routing variability and translation issues. This protocol requires a vetted telephony partner and an IP-level SIP trunk configuration between the partner's SBC and Salesforce's SBC.

For details, see Configure the Channel and Telephony Settings for SIP.

Dynamic Routing

Send an API request for Salesforce to dynamically allocate a routable number. Use this phone number to transfer the call to the agent.

• Regional availability: Global (where supported)
• Call travels over: Hybrid (phone network + internet)
• Call context passed to Salesforce: Full context via the Voice Context Registry. See Connect Related Voice Calls When Using SIP or Dynamic Routing.
• Partner requirement: Any partner contact center that can make an API call

Choose Dynamic Routing if you need to support callers outside the US and Canada, don't use Genesys or Vonage, or want to expand globally without additional telecom licensing.

Note Agentforce Voice with Dynamic Routing doesn't support voice call recording.

For details, see Configure Telephony Vendor Settings When Using Dynamic Routing.

Comparison Summary of Communication Protocols

To help you choose the right communication protocol to transfer incoming calls to the agent, review the comparison in this table.