# SIP Troubleshooting Checklists

## SIP Connection Information

| Property                      | Value in EU-Production | Value in EU-Staging    | Value in US-Production |
|-------------------------------|------------------------|------------------------|------------------------|
| Inbound SIP-Proxy             | sip.cognitivevoice.io  | sip.demo.join-us.cloud | sip.atl.join-us.cloud  |
| Inbound SIP-Proxy IP          | 145.14.231.149 | 145.14.231.171 | 204.124.15.179 |
| Inbound SIP-Proxy Port        | 5060/UDP (plain),<br>5060/TCP (plain),<br>5061/TCP (TLS) | 5060/UDP (plain),<br>5060/TCP (plain),<br>5061/TCP (TLS) | 5060/UDP (plain),<br>5060/TCP (plain),<br>5061/TCP (TLS) |
| Outbound SIP-Proxy IP         | 145.14.231.153 | 145.14.231.175 | 204.124.15.183 |
| RTP Port-Range<br>(inclusive) | Start: 50000/UDP<br>End: 57999/UDP | Start: 50000/UDP<br>End: 57999/UDP | Start: 25000/UDP<br>End: 64999/UDP |

## General Notes

* No whitelisting is necessary in CVG, any valid SIP communication is accepted and appropriate responses are sent out.

## OPTIONS

* The CVG SIP proxies will generally answer to SIP OPTIONS ping.
* Use a sensible User-Agent header because pings from commonly known scanner utilities will not be answered.
* SIP OPTIONS pings must be properly addressed to the CVG endpoint. E.g. the Request-URI must refer to our inbound proxy, e.g. `OPTIONS sip:sip.cognitivevoice.io ...`

## INVITE

* Call destinations must be international phone numbers with a leading country code in either `+49...` or `0049...` formats. Other formats or amounts of leading zeros may lead to call rejection.
* The request URI must refer to our inbound proxy, e.g.: `INVITE sip:+4944444444@sip.cognitivevoice.io`. Using the IP address and optionally an explicit SIP port (5060 or 5061 for TLS) is also fine.
* The SIP URI in the `From` header must never refer to any of our SIP proxies. E.g. `From: Someone <sip:+4944444444@sip.cognitivevoice.io>` would _not_ be valid since this would identify the user as a local user.
* If no `Privacy` header is sent, then SIP addresses in the `From` header will be considered anonymous/supressed, if the display name is `anonymous`, the user-port of the URI is `anonymous` _or_ the host ends with `.invalid`. All checks are done case-insensitive.

## REFER

* CVG does *not* accept REFER requests, however it is possible to REFER calls to CVG and it is possible to send out REFER requests from CVG using the [`/call/refer`](/specs/#/call/refer) API.

## Encryption

* Make sure the SIP communication works without encryption before enabling it!
* TLS/SIP in combination with SRTP-SDES is supported using modern TLS 1.2 and TLS 1.3 cipher suites (this is usually used from contact center solutions).
* TLS/WSS in combination with SRTP-DTLS is supported using modern TLS 1.2 and TLS 1.3 cipher suites (this is usually used for WebRTC).
* Support for specific cipher suites can be probed using the `curl` command line tool via the URL `https://sip.cognitivevoice.io:5061`.

## Audio

* Advertised Codecs are: G.722, OPUS, G.711a and G.711u (prioritized in this order)