Firebox T15 and a Fritzbox as SIP Telephone appliance


i have an issue with a T15 and a fritzbox 7272.

The 7272 only does one thing .... it provides the telekomunication link (SIP) for my customer. This works most of the time but....


TAE --> Modem --> Watchguard (VLAN7 PPPoE) --> Fritzbox 7272 with telefony enabled

I made SIP Rules (Packet Filters: from External to Trusted and from Trusted to External) that allow Ports to the Fritzbox to be open.

Ports i opened so far:
Portrange 7078-7097
Portrange 3478-3479
Portrange 30000-310000
Portrange 40000-41000

For TCP and UDP
Telekom VLAN 7

Everything looks good but sometimes the customer can not be called nor can a FAX be sent.

Spoke with telekom and they say the Internetconnection and the Teleefone Numbers are fine...

Spoke with watchguard and they told me that maybe the Fritzbox is dying because they could not figure out what happens...

Spoke with AVM and they told me that the 7272 is out of service and if i wanted help i deeded to by a new model :/

Maybe someone has a hint here

Thank You


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    Most VoIP providers I have talked to say to let everything outbound unrestricted from their phones or VoIP adapters. I have an Obihai Obi202 VoIP phone adapter and I have it on a separate VLAN and let it out unrestricted. My phones connected to its analog port all work without issue.

    Maybe that information will help?

    Gregg Hill

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