# Twilio SIP Trunk

[Twilio's Elastic SIP Trunking](https://www.twilio.com/docs/sip-trunking) service automatically scales, up or down, to meet your traffic needs with unlimited capacity. In just minutes you can deploy globally with our easy-to-use self-service tools without having to rely on slow providers. Discover everything you’ll need to take control of your connectivity with Twilio Elastic SIP Trunking.

[Twilio’s Elastic SIP Trunking](https://www.twilio.com/docs/sip-trunking) is effectively a "pipe" that connects an enterprise’s SIP infrastructure to the PSTN. This allows you to make calls from your network to the Public Domain for PSTN access (Termination), and receive calls on Twilio phone numbers on your network (Origination).

<figure><img src="/files/BHjQfFkU53KUJiFa9z9m" alt=""><figcaption></figcaption></figure>

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PortSIP PBX integrates with Twilio Elastic SIP Trunking to support voice calls and SMS/MMS messaging, enabling quick and straightforward deployment.

This article covers the following topics:

* [Purchase a DID on the Twilio Platform](/portsip-communications-solution/configuring-sip-trunks/twilio-sip-trunk/purchase-a-did-on-the-twilio.md)
* [Configuring Twilio Register Based Trunk](/portsip-communications-solution/configuring-sip-trunks/twilio-sip-trunk/configuring-twilio-register-based-trunk.md)
* [Configuring Twilio Interconnect Trunk](/portsip-communications-solution/configuring-sip-trunks/twilio-sip-trunk/configuring-twilio-interconnect-trunk.md)
* [Configuring Outbound & Inbound Calls](/portsip-communications-solution/configuring-sip-trunks/twilio-sip-trunk/configuring-outbound-and-inbound-calls.md)
* [Twilio SMS Integration](/portsip-communications-solution/configuring-sip-trunks/twilio-sip-trunk/twilio-sms-integration.md)


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