> For the complete documentation index, see [llms.txt](https://docs.bird.com/connectivity-platform/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.bird.com/connectivity-platform/voice-calls/how-to-receive-a-call.md). # How to receive a call You can forward incoming calls on any number of your choice via our [Flow Builder](https://dashboard.messagebird.com/en/flow-builder/) or through the API. **Flow builder** When you have purchased a Voice-enabled virtual mobile number, you can easily forward all incoming calls to another phone number or SIP URI by using our [Flow Builder](https://dashboard.messagebird.com/en/flow-builder). Check [How to forward calls to another phone number or SIP URI](/connectivity-platform/how-to-guides/how-to-forward-calls-to-another-phone-number-or-sip-uri.md) for a step by step guide on how to set this specific flow. **Forwarding to SIP (SIP URI formatting)** When forwarding the incoming calls to a SIP trunk, please use the format below to insert your SIP URI: "sip:\@\"\ for example: *sip:*[*+31612345678@sip.domain.com*](mailto:+31612345678@sip.domain.com) **Signalling IP's** You may whitelist below signalling IP's when receiving calls on your own SIP URI: * Asia: 35.186.152.240 * Europe: 104.199.82.179 * US: 104.196.15.81 Media IPs: \- 104.199.61.220 \- 104.199.69.60 \- 104.196.222.116 \- 35.185.41.80 \- 35.186.148.117 \- 35.186.147.231 **Voice codecs:** MessageBird supports the following codecs: * PCMA (G711a) * PCMU (G711u) --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.bird.com/connectivity-platform/voice-calls/how-to-receive-a-call.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.