Pinging @AndrewZ and @IceG as they are the LTE modems experts.
Hi guys. I'm using an LTE service with my MF286D router, running OpenWrt 24.10.0, for WAN failover. The mobile plan includes unlimited domestic phone calls that I'd like to use, since (as you guys know) this router's FXS ports work on OpenWrt, as they're managed by the LTE modem (firmware BD_TELIAMF286DV1.0.0B12).
Calls work both ways with an analogue telephone, but I'd like to use my Fritzbox 7590 instead, running the latest FirtzOS 8.02, so I can make and receive phone calls while I'm travelling.
With the Fritzbox (connected via its FXO port) incoming calls work but outgoing calls don't. The likely cause is that the MF286D FXS ports produce a weird dial tone, it sounds like a busy tone but with longer tones and silences of the same length, and probably the Fritzbox doesn't recognize that, nor does an old Cisco voice gateway (1751-V, IOS too old to mention...) with lots of options on its FXO ports.
Trying to change the dial tone, I looked at uqmi commands but I couldn't see anything relevant.
I found this post suggesting it's a Swedish tone, but I checked cptone SE on the Cisco VG and it's a continuous tone.
Next I tried an adb shell to the modem and looked in most places but I couldn't find any relevant configuration.
Any pointers to what to try next? Since the modem has a Telia firmware, an actual Swedish tone would probably be okay for the Fritz, or worst case I could use the Cisco, though it doesn't support caller-id on its FXO ports, it's too old for that.
I'd gladly avoid it, but unfortunately in this case it's unavoidable, as it's the only way to use the MF286D's VoLTE capability.
In my opinion it does have to do with OpenWrt, as the router is running it. It's a popular router and one of the very few exceptions of devices with working FXS ports, so I think this belongs here, and it could be useful to other OpenWrt users who own this device.
I could have posted this on the Polish forum I linked to above, that has a dedicated, large thread about this router, but I posted it here so it could be of reference to other OpenWrt users in the future.
Maybe @IceG has some specific tips for this thread, if not I'll ask the question on the Polish forum.
Router is not running it, the modem in the mf286d runs a cut down version of android and the FX ports are directly connected to the modem.
It's nothing to do with Openwrt.
With #11* I still get the same tone coming from the MF286D, the Fritzbox probably interprets it as a busy tone, relays it back to the caller and disregards any further dialing. Anyway, I'll continue this on the other forum as it's not welcome here.
Yes, I had looked at that AVM article and tried some of the suggested solutions.
