VAPI•4mo ago

SIP Dynamic IP Problem

Hello everyone.
I have a private SIP server. I've configured my SIP Trunk Credentials.
(The "Use SIP register" option is enabled.)
I can successfully register to my server.
The problem is this:

VAPI has two IP addresses:
44.229.228.186/32
44.238.177.138/32

When registering, it uses 44.238.177.138.

It randomly uses these two IP addresses for each call attempt.

If the call originates from the registered address, 44.238.177.138, it succeeds.
If it originates from 44.229.228.186, it gets rejected.

I've played around with many settings on my server (NAT, Peer, Permit, Host), but nothing has changed.
I appreciate your help.
Thank you.

Vapi Support BotAPP•9/11/25, 10:27 PM

Suggestion:
Make sure your SIP server is configured to allow both Vapi IP addresses for SIP signaling and media. For example, in an Asterisk sip.confsip.conf peer definition, you can use:

permit=44.229.228.186/32
permit=44.238.177.138/32

permit=44.229.228.186/32
permit=44.238.177.138/32

This ensures calls from either Vapi IP will be accepted.
For more details, see the Vapi SIP trunk documentation.

Source:

SIP trunk documentation

⤵️ Mention @Vapi Support Bot for follow-ups 🐥

KyleAPP•9/15/25, 4:30 PM

Hi muratyilmaz.dev,

For SIP dynamic IP issues, it's crucial to ensure that your network settings align with Vapi's requirements. If you're using IP-based authentication, consider issues that might arise from changing IPs. Here are the steps you can take:

Allowlist Static IPs: Ensure your network allows traffic to Vapi's static IPs:
```
44.229.228.186/32
```
```
44.229.228.186/32
```
and
```
44.238.177.138/32
```
```
44.238.177.138/32
```
. These are exclusively used for SIP traffic.
Authentication: IP-based authentication can be unreliable if your telephony provider does not offer a unique termination URI or dedicated SIP server. Providers like Plivo and Twilio support unique domains which could mitigate this.
Configuration Check: Verify that your SIP trunk configuration in Vapi is properly set up with correct gateway and authentication details. Use SIP credentials as an alternative if IP-based methods are unstable.

If adjustments are needed in your authentication method or network configurations, consult your SIP provider for any specific settings they require for dynamic IP support.

For further steps on configuring your SIP trunk, refer to the SIP Trunking documentation.

SIP Dynamic IP Problem

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