@MikaKpk Well, #FritzBox supoorts call routing and if you din't have one, they are cheap af used…

• Cheap #VoLTE routers will spit you out an RJ-11 jack you can hookup to the #FritzBox's #DSL port whilst having it not act as #Modem.

• Better #VoLTE boxes, often called "#GoIP" or "#GSMoverIP" literally run an #Asterisk server on them, some even can do Multi-SIM & call routing themselves or just expose each SIM as a SIP connection to link a #VoIP phone / #PBX to.

You'll find a crapton of those on Aperzon, eNay & ShitExpress!

• The Tenda 4G06 is just the cheapest I could find with an actual brand name attached to it…

Most people ain't aware of the search terms for a "#FixedWirelessTerminal"…

• Personally, I did use such boxes to migrate seniors from landline to #GSM & #LTE whilst letting them keep their (accessible, hearing-aid compatible) desktop handset.