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Twilio SIP: Connect to Twilio with SIP

Connect your SIP endpoints to Twilio and start building voice apps with Twilio’s APIs and application stack. Also, once you’ve connected with Twilio, you can route your calls to any phone, browser, mobile app, or any other SIP endpoint. And best of all, SIP already works with all your existing Twilio apps.

What’s SIP?

Session Initiation Protocol (SIP) is a protocol used to establish and manage communications session between IP endpoints, typically for voice calls. Twilio supports both sending and receiving SIP so that you can easily route voice calls between Twilio and your SIP endpoints.

Sending SIP to Twilio

Learn how to get started connecting to Twilio from your SIP endpoints.

Receiving SIP from Twilio

Learn how to get started connecting to your SIP endpoints from Twilio.

SIP Connection - Technical Specifications

To connect with Twilio via SIP, you need to whitelist the Twilio’s IPs for both SIP and media traffic. Also, check that your SIP endpoint supports the same media codec and method for sending and receiving DTMF.

SIP traffic

Twilio sends SIP traffic from a set of IP addresses. The IP address of a request may change from call to call. You must whitelist all of Twilio’s SIP IPs so that all traffic can reach you.

Media traffic

Media is transported via RTP and you will need to whitelist port 10000 to 20000 for RTP traffic. Also, RTP traffic will come from a variable set of IPs so you will need to open up your system to receive RTP from any IP address.

Media codec

Twilio uses G.711/μ-law for media.

DTMF

Twilio uses RFC2833 for sending and receiving DTMF.

TLS

Twilio supports TLS but does does not currently validate the certificates of the remote clients. This means that you may use self-signed certs on your clients.

IP Addresses for SIP traffic

Twilio will send SIP traffic from one of the IP addresses below. We strongly recommend that you whitelist all of the IPs below even though you may only see traffic from a few IPs initially. The additional IPs will be used to enhance scalability and reliability.

North American Gateways:
107.21.222.153
107.21.211.20
107.21.231.147
54.236.81.101
54.236.96.128
54.236.97.29
54.236.97.135
South American Gateways (reserved for future use):
54.232.85.81
54.232.85.82
54.232.85.84
54.232.85.85
European Gateways (reserved for future use):
54.228.219.168
54.228.233.229
176.34.236.224
176.34.236.247
Asian Gateways (reserved for future use):
46.137.219.1
46.137.219.3
46.137.219.35
46.137.219.135
54.249.244.21
54.249.244.24
54.249.244.27
54.249.244.28