Most Fritz!Box VoIP configurations have a phone number configured to only work on telephony devices (i.e. handsets) on the same Fritz!Box.
But it is possible to define a telephony device that itself is another VoIP end-point.
This way you can hook a second (or more) Fritz!Box up to the phone number(s) of the first Fritz!Box.
I am using this for two reasons:
- the second Fritz!Box was the primary one, but is not supported by your VoIP provider any more (this happened after a forced migration from xs4all to KPN: VoIP would not work no matter I tried: Many links about free modem/router choice and their configurations for the Dutch KPN internet/VoIP provider)
- you have a LAN2LAN VPN between multiple locations and want to use the same phone numbers from different LAN locations (beware of LAN2LAN error messages; see Reminder that the Fritz!Box IKE error 0x1C is still barely documented: crucial places like the built-in help page point to non-existing URLs)
Below is how to get this going, assuming the first Fritz!Box is a 7490 running firmware 7.29 and the second is a a 7360 with firmware 6.33 (other versions and firmware versions vary slightly).
But first the related post: Many links about free modem/router choice and their configurations for the Dutch KPN internet/VoIP provider where I figured out that just using a 7360 won’t cut it any more.
The Wiert Corner - irregular stream of stuff 