I am aware that there are devices where you plug a SIM card and they will emulate RJ11 for an old school phone (e.g. this ). I would however need the device to connect to (not provide!) WiFi and be able to make WiFi calls via the RJ11 the same way contemporary cell phones make WiFi calls (i.e. to the other party it looks just like a call from the number associated with the SIM). Is there a device like that?

Background: An elderly relative had an old school press-button GSM phone and was able to use it with some struggle, but now they've moved to a different care home with poor GSM signal, but good WiFi (and no RJ11 outlets). We bought them a newer phone with support for WiFi calls and it appears to be a step too far and they can't really adapt to even pick up calls reliably. So the idea is to get them an old school cable phone (which they can operate well), using the same SIM as all their friends have and use their GSM number. They are also no longer able to go outside alone, so the safety considerations which motivated introducing a GSM phone for them initially are no longer relevant.

If there is other way to achieve this setup (same phone number, calls over WiFi) it is also welcome.

  • What do you mean by calls over "WiFi"? Do you intend to use a VoIP service that gives the person a phone number that can be called like any other phone? Or are you using something that is entirely internet-based to call them?
    – Romen
    Commented Dec 4, 2023 at 17:51
  • @Romen The cell provider uses WiFi calls in the sense of en.m.wikipedia.org/wiki/Wi-Fi_calling i.e. it is not VoIP, rather a separate (?) standard with seamless handover between cellular signal and Wi-Fi. I'd prefer not setting up a separate VoIP number. Commented Dec 4, 2023 at 19:09
  • 2
    Hi Martin, welcome to Hardware Recs! Is there enough of a signal that a cellular data booster might work? If so, that's probably the cheapest and easiest solution. If not, does it have to be a GSM phone, or could you use CDMA? At least in the US, Verizon is the only cell provider that still offers an LTE network extender rather than a cellular booster; AT&T used to offer the MicroCell, but it was discontinued in 2017. Failing that, Wi-Fi calling is your only bet.
    – JMY1000
    Commented Dec 5, 2023 at 2:58
  • @JMY1000 I'm in the EU, so not sure how similar the situation is, but no, I don't need any specific single standard of cellular connection. Commented Dec 5, 2023 at 11:12


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