🔌 Supported Transports

We support the following SIP transports:

SIP UDP on port 5060
SIP TCP on port 5060
SIP TLS+SRTP on port 5061

🔢 SIP and RTP Subnets

Europe

SIP DNS

eu.sip.callr.com

SIP IP

185.76.20.162/32

185.76.22.162/32

RTP

185.76.20.64/28

185.76.22.64/28

USA

SIP DNS

usa.sip.callr.com

SIP IP

52.14.84.104/32

RTP

18.221.24.70/32

18.220.223.254/32

ℹ️
Webhooks and fetch
These ranges only cover SIP signaling and RTP media. HTTP requests sent by Callr (Webhooks and fetch@v3) come from the ranges listed in IP Subnets.

#️⃣ Number format

Phone numbers should always be E.164 prefixed by "+". An INVITE R-URI should look like this:

INVITE sip:[email protected] SIP/2.0

⬅️ Outbound SIP

To make a call to a SIP endpoint, you can use dial@v2 in a Callr Actions scenario.

Here is an example dialing to an OpenAI Realtime agent (see Connect to OpenAI for the full setup, including the webhook your server needs):

description: Dial to SIP

compat:
  version: "2025-09-01"

defaults:
  autoAnswer: false

branches:
  inbound-call:
    actions:
      - action: dial@v2
        params:
          targets:
            - number: sip:[email protected];transport=tls
              timeout: 60

Other guides: Connect to ElevenLabs, Connect to Vapi.