Grandstream UCM6208 and Snom300 audio issue

Im having issues with my intercom system. When we dial the extension the phone picks up. But there is no audio. We recently switched out our firewall.

1/7/2023 17:34:46 [CRITIC] PHN: SIP: packet 1000279 dest invalid udp: for Request DISCOVER/-
1/7/2023 17:34:46 [WARN ] PHN: SIP: process_registrar_packet: 401 needs 128 bit nonce
1/7/2023 17:34:46 [NOTICE] PHN: SIP: process auth:Match challenge for user=300, realm=grandstream
1/7/2023 17:34:46 [CRITIC] PHN: SIP: Registered at registrar as [email protected]:9998 (Expires: 3599 secs

If your the phone and the PBX are on the same LAN subnet, the traffic would usually not be passing through the firewall at all. Possibly, if they are (directly or through switches) connected to different LAN ports on a sophisticated firewall that doesn’t simply bridge the ports together, there might be rules that could block traffic. You can rule this out by temporarily connecting two phones and the PBX to ports on the same switch, to ensure that the firewall is not causing your issue.

If only one extension is failing this way, it’s likely the phone or its configuration. If all extensions are failing, please note:
This is a FreePBX forum. Although Grandstream PBXes use Asterisk, it’s heavily modified and locked down, so members of this forum are unlikely to understand the errors you are seeing. There is no FreePBX code on a Grandstream device. I suggest that you post at . Possibly, you may get help at ; paste the complete log for a failing call at and post the link.

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