SIP

Session Initiation Protocol (SIP) is a signaling protocol for initiating, terminating and modifying user sessions over an IP network.

Using SIP to connect to Twilio is one way to get access to Twilio's global reach and powerful automation and scripting functions.

You can connect your on-site or virtual Private Branch Exchange (PBX) with Twilio's servers. Here's our overview of connecting your existing SIP communications infrastructure to us.

Dig into our API Reference docs for Twilio's SIP Domains:

• SIP Credential Resource
• SIP CredentialListResource
• SIP CredentialListMappingResource
• SIP DomainResource
• SIP IpAccessControlList Resource
• SIP IpAccessControlListMapping Resource
• SIP IpAddress Resource

You can create and configure SIP Domains, IP Access Control Lists, and Credential Lists in Twilio Console or in the legacy Console.

On a SIP Domain's details page, you can see all devices registered with the Domain. Each entry shows the contact address, user agent, registration source IP, and expiration time. Use this to confirm registrations succeeded and to troubleshoot clients that aren't reachable.

Registrations are Region-specific — endpoints only appear in the Region where the SIP Domain is routed. See Regional SIP Domains for more on Region routing.

Secure Media enforces SRTP for media on calls to and from the SIP Domain. When Secure Media is enabled, Twilio rejects calls that don't negotiate SRTP. Make sure your SIP clients and SBCs are configured for SRTP before enabling this setting in production.

A SIP Domain can exist in multiple Twilio Regions but is only active in one Region at a time.

See Regional SIP Domains for details.