SIP
Learn how Session Initiation Protocol (SIP) acts as a signaling protocol to manage user sessions over an IP network, allowing you to connect your existing communications infrastructure to Twilio.
You can use this guide to create self-service automation, build inbound contact centers, manage outbound contact centers, and establish PSTN connectivity.
See Related reference documentation to learn more about the SIP resources used in this guide.
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.
Info
For information about SIP Trunking with Twilio, check out our Elastic SIP Trunking documentation.
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.
In Twilio Console, go to Voice > SIP domains, select your SIP Domain, and then open the Registered endpoints tab.
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.
- In Twilio Console, go to Voice > SIP domains and select your SIP Domain.
- On the Secure media card, select Enable secure media.
A SIP Domain can exist in multiple Twilio Regions but is only active in one Region at a time.
- In Twilio Console, go to Voice > SIP domains and select your SIP Domain. The Active region section shows which Region is active.
- To change the active Region, select Change active region, select the target Region, and then select Update region.
See Regional SIP Domains for details.
This guide covers a feature that can support the following use cases:
You can use the interaction between SIP and TwiML to automate outbound calls that gather user input from your SIP endpoint. For example, you can use the <Gather> verb to collect DTMF tones from a caller and route them through your PBX.
To learn more advanced features that you can use with self-service automation, see Voice self-service automation.
By connecting your SIP infrastructure, you can route incoming calls from the PSTN through Twilio directly to your existing contact center equipment or softphones.
To learn more advanced features that you can use with inbound contact centers, see Voice inbound contact center.
You can use SIP to allow your agents to place outbound calls through Twilio's global network while maintaining your current call control environment.
To learn more advanced features that you can use with outbound contact centers, see Voice outbound contact center.
You can use SIP to bridge your private IP network with the public switched telephone network, enabling global reach for your existing SIP-based communications.
To learn more advanced features that you can use with PSTN connectivity, see Voice PSTN connectivity.
Explore the following guides to build on what you've learned in this guide:
- How to add programmability to your existing SIP network: Add Twilio's powerful scripting capabilities to your current infrastructure.
- How to route calls to your SIP network with an outbound call: Direct traffic from Twilio to your SIP endpoints.
- Making SIP calls: Start placing calls using the SIP interface.