Problem with PBX

Hey, we upgraded our Alcatel lucent pbx to use voip. The Firebox is using pppoe to connect to isp. For that I opened some ports given by the isp. I did this by creating a static nat to pbx. Additionally I added the sip-alg proxy. All worked fine until last friday. Now calls ends automatically after about 10s and no voice is transmitted. I checked some logs and recorded a trace. It seems that the firebox is blocking all incoming rtp data. SIP in and outgoing passes. The firebox also transfers outgoing rtp data. It would be nice if someone could help me


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    Consider opening a support case on this.

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    james.carsonjames.carson Moderator, WatchGuard Representative

    Hi @Jonas

    In general, unless under very specific circumstances, most VoIP providers will suggest not using SIP-ALG. In most circumstances, it's there to help with devices that don't do NAT traversal well. If the device does NAT traversal by itself (for example, via STUN) it will break the SIP-ALG and cause issues.

    If SIP-ALG is needed, it's likely something is wrong with registration data, and the firebox is sending the RTP data elsewhere (or simply doesn't know where to send it.) I'd suggest opening a support case so we can help determine what is specifically going on.

    -James Carson
    WatchGuard Customer Support

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