{"templateId":"markdown","sharedDataIds":{},"props":{"metadata":{"markdoc":{"tagList":[]},"product":"Voice v2 (preview)","type":"markdown"},"seo":{"title":"SIP Trunking | Voice API v2 | Sinch","siteUrl":"https://developers.sinch.com","llmstxt":{"title":"Sinch Developer Documentation","description":"LLMs.txt containing a map of all the documentation files for Sinch.","sections":[{"title":"Numbers API","description":"The Numbers API enables you to search for, view, and activate numbers. It's considered a precursor to other APIs in the Sinch product family. The numbers API can be used in tandem with any of our APIs that perform messaging or calling.","includeFiles":["docs/numbers/**/*.md","docs/numbers/**/*.yaml"],"excludeFiles":["docs/numbers/index.md"]},{"title":"Conversation API","description":"Send and receive messages globally on many popular channels with ease and confidence when using Sinch's Conversation API. Conversation API is the preferred API for sending mobile messages on SMS and other social channels with Sinch. It is a simple API with unified error messages, consistent request payloads, and common webhook payloads that are channel-agnostic.","includeFiles":["docs/conversation/**/*.md","docs/conversation/**/*.yaml"],"excludeFiles":["docs/conversation/index.md"]},{"title":"Voice API","description":"The Voice API works as a big telephony switch. The Voice API handles incoming phone calls (also known as incoming call “legs”), sets up outgoing phone calls (or outgoing call “legs”), and bridges the two. The incoming call leg may come in over a data connection (from a smartphone or web application using the Sinch SDKs) or through a local phone number (from the PSTN network). Similarly, the outgoing call leg can be over data (to another smartphone or web application using the Sinch SDKs) or the PSTN network.","includeFiles":["docs/voice/**/*.md","docs/voice/**/*.yaml"],"excludeFiles":["docs/voice/index.md"]},{"title":"Voice API v2","description":"The Voice API works as a big telephony switch. The Voice API handles incoming phone calls (also known as incoming call “legs”), sets up outgoing phone calls (or outgoing call “legs”), and bridges the two. The incoming call leg may come in over a data connection (from a smartphone or web application using the Sinch SDKs) or through a local phone number (from the PSTN network). Similarly, the outgoing call leg can be over data (to another smartphone or web application using the Sinch SDKs) or the PSTN network.","includeFiles":["docs/voice-2.0/**/*.md","docs/voice-2.0/**/*.yaml"],"excludeFiles":["docs/voice-2.0/index.md"]},{"title":"Verification API","description":"The Verification API is a platform for phone number verification. It consists of the API and different software development kits (the Sinch SDKs) that you integrate with your smartphone or web application and cloud based back-end services. Together they enable SMS, Flashcall, Phone Call and Data verification in your application.","includeFiles":["docs/verification/**/*.md","docs/verification/**/*.yaml"],"excludeFiles":["docs/verification/index.md"]},{"title":"Provisioning API","description":"Provisioning API allows you to programmatically set up your senders, accounts and templates on your favorite messaging platforms on the Conversation API. For now, you can create your first WhatsApp channel through Meta's Embedded sign up, you can configure your first SMS App and configure your webhooks. As development continues, we will be adding the most commonly used channels.","includeFiles":["docs/provisioning-api/**/*.md","docs/provisioning-api/**/*.json"],"excludeFiles":["docs/provisioning-api/index.md"]},{"title":"Elastic SIP Trunking API","description":"With Elastic SIP Trunking you can create and manage your SIP trunks and phone numbers programmatically.","includeFiles":["docs/est/**/*.md","docs/est/**/*.yaml"],"excludeFiles":["docs/est/index.md"]},{"title":"Fax API","description":"Send and receive HIPAA compliant faxes on our modern fax platform using our developer-friendly API.","includeFiles":["docs/fax/**/*.md","docs/fax/**/*.yaml"],"excludeFiles":["docs/fax/index.md"]},{"title":"In-app Voice and Video SDK","description":"The In-app Voice and Video SDK enables you to add voice and video calling capabilities directly into your mobile or web application using the Sinch SDKs.","includeFiles":["docs/in-app-calling/**/*.md"],"excludeFiles":["docs/in-app-calling/index.md"]},{"title":"Number Lookup API","description":"The Number Lookup API is designed to provide in-depth information about phone numbers, helping enterprises enhance their communication strategies and prevent fraud. By identifying the type of phone line (for example, mobile, landline, VoIP) and the associated carrier, the API allows businesses to optimize routing, reduce unnecessary costs, and improve customer engagement.","includeFiles":["docs/number-lookup-api-v2/**/*.md","docs/number-lookup-api-v2/**/*.yaml"],"excludeFiles":["docs/number-lookup-api-v2/index.md"]},{"title":"Functions","description":"Serverless compute for voice and messaging. Deploy your code and Sinch routes live calls and messages to it — no infrastructure to run.","includeFiles":["docs/functions/functions/**/*.md","docs/functions/concepts/**/*.md","docs/functions/reference/**/*.md"],"excludeFiles":["docs/functions/functions/index.md"]},{"title":"CLI","description":"One command line for every Sinch API and the full Functions lifecycle — scaffold, run locally, deploy, and manage.","includeFiles":["docs/functions/cli/**/*.md"],"excludeFiles":["docs/functions/cli/index.md"]}]},"description":"This document provides a overview of Sinch SIP trunking service."},"dynamicMarkdocComponents":[],"compilationErrors":[],"ast":{"$$mdtype":"Tag","name":"article","attributes":{},"children":[{"$$mdtype":"Tag","name":"Heading","attributes":{"level":1,"id":"sip-inbound","__idx":0},"children":["SIP Inbound"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":[{"$$mdtype":"Tag","name":"strong","attributes":{},"children":["Sending calls to Sinch platform from your SIP infrastructure"]}]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["SIP Inbound calls are calls that are being routed from your SIP infrastructure to the Sinch platform through a SIP interconnection/trunk."]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":[{"$$mdtype":"Tag","name":"img","attributes":{"src":"/assets/spider_sip_inbound.bef339a3bc6c754d03bf4849b88ea3ecffe5acf7d8604e89240a7992b8200d53.c43d86dc.png","alt":"Diagram showing SIP Inbound flow"},"children":[]}]},{"$$mdtype":"Tag","name":"Heading","attributes":{"level":3,"id":"sinchs-sip-inbound-uris","__idx":1},"children":["Sinch's SIP Inbound URIs"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Sinch operates voice services in multiple geographical regions. You can configure your SIP infrastructure to use any of the following Sinch geographical locations:"]},{"$$mdtype":"Tag","name":"blockquote","attributes":{},"children":[{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Europe:"," ","euc1.vp.sip.sinch.com"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["North America:"," ","use1.vp.sip.sinch.com"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["South America:"," ","sae1.vp.sip.sinch.com"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Southeast Asia:"," ","apse1.vp.sip.sinch.com"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Australia:"," ","apse2.vp.sip.sinch.com"]}]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["The above FQDNs provide redundancy. Use these as a Inbound SIP URI in your communications infrastructure to direct SIP traffic towards Sinch. For each region there are several IP addresses used for reliability purposes (see current IP address/CIDR block in allowlists section). Each of these IP addresses represents a unique public edge for our SIP Trunking services, distributed across multiple Availability Zones."]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Both UDP and TCP are supported for calls terminating to Sinch."]},{"$$mdtype":"Tag","name":"ul","attributes":{},"children":[{"$$mdtype":"Tag","name":"li","attributes":{},"children":["If you can't use FQDNs, reach out to support@sinch.com."]}]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Once the call arrives in the Sinch platform, your backend will get an Incoming Call Event callback, notifying of the incoming call. You can control how you would like the call to be connected by responding to this event. For details on how and what you can respond, check out ",{"$$mdtype":"Tag","name":"MarkdownLink","attributes":{"href":"/docs/voice/api-reference/voice/callbacks/"},"children":["Callback API"]},". If no callback is specified in Sinch Build Portal, Sinch will try to terminate your call to PSTN using ",{"$$mdtype":"Tag","name":"em","attributes":{},"children":["To address"]}," in your incoming SIP message as destination phone number."]},{"$$mdtype":"Tag","name":"blockquote","attributes":{},"children":[{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Make sure that any phone number sent via SIP to Sinch is always E.164-formatted (e.g ",{"$$mdtype":"Tag","name":"em","attributes":{},"children":["+12345678900"]},")."]}]},{"$$mdtype":"Tag","name":"Heading","attributes":{"level":3,"id":"authentication","__idx":2},"children":["Authentication"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["In order to use a trunk for Inbound it must have a Inbound SIP URI and at least one authentication scheme, see below."]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["You need to authenticate your SIP infrastructure to make outbound calls via the Sinch SIP trunk:"]},{"$$mdtype":"Tag","name":"blockquote","attributes":{},"children":[{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Host: {region}.vp.sip.sinch.com"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Username/Authentication name: Your Sinch service Key"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Password: Your Sinch service Secret"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Realm: {region}.vp.sip.sinch.com"]}]},{"$$mdtype":"Tag","name":"Heading","attributes":{"level":3,"id":"allowed-caller-id-number-cli-for-terminating-calls","__idx":3},"children":["Allowed caller ID number (CLI) for terminating calls"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["You must specify a caller ID number that corresponds to a Sinch DID on your account or a phone number verified in your Sinch Build Portal."]},{"$$mdtype":"Tag","name":"Heading","attributes":{"level":3,"id":"sip-inbound-example","__idx":4},"children":["SIP Inbound example"]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":["Example SIP INVITE sent to Sinch with SIP Inbound:"]},{"$$mdtype":"Tag","name":"CodeBlock","attributes":{"data-language":"shell","header":{"controls":{"copy":{}}},"source":"> Request-Line: INVITE sip:+12345678900@euc1.vp.sip.sinch.com SIP/2.0\n>\n> From: \"+19876543210\" <sip:+19876543210@euc1.vp.sip.sinch.com>;tag=0c1e59a1af\n>\n> To: <sip:+12345678900@euc1.vp.sip.sinch.com>\n>\n> Contact: \"+19876543210\" <sip:+19876543210@10.186.9.38:51103;ob>\n","lang":"shell"},"children":[]},{"$$mdtype":"Tag","name":"p","attributes":{},"children":[{"$$mdtype":"Tag","name":"br","attributes":{},"children":[]},{"$$mdtype":"Tag","name":"br","attributes":{},"children":[]}]}]},"headings":[{"value":"SIP Inbound","id":"sip-inbound","depth":1},{"value":"Sinch's SIP Inbound URIs","id":"sinchs-sip-inbound-uris","depth":3},{"value":"Authentication","id":"authentication","depth":3},{"value":"Allowed caller ID number (CLI) for terminating calls","id":"allowed-caller-id-number-cli-for-terminating-calls","depth":3},{"value":"SIP Inbound example","id":"sip-inbound-example","depth":3}],"frontmatter":{"seo":{"title":"SIP Trunking | Voice API v2 | Sinch","description":"This document provides a overview of Sinch SIP trunking service."}},"lastModified":"2026-08-31T15:45:25.000Z","pagePropGetterError":{"message":"","name":""}},"slug":"/docs/voice-2.0/api-reference/phone/inbound","userData":{"isAuthenticated":false,"teams":["anonymous"]},"isPublic":true}