Hey, I’m having an issue where if I have both VoLTE and VoWi-Fi enabled, all incoming calls over the mobile network show up as “Unknown caller”.
This is not an issue that the caller is not in my address book - the caller’s number is not even known to the phone. If I try to call back, I can’t - because the phone doesn’t know what number called it.
I’m using a physical sim of the Polish branch of the “Mobile Vikings” carrier. They’re a MVNO that uses the infrastructure of the Polish carrier called “Play”.
Is this something that will be resolved by a software update as the phone matures? Or something to talk to the carrier about?
If I disable volte and vowifi the number appears correctly, and the Google default dialer app matches the number to a contact I have correctly. I can also call back fine, as the caller’s number is saved.
I was using the Polish branch of the carrier “Mobile Vikings”, which is a MVNO of the Play carrier. VoLTE and Vo-WiFi didn’t work.
Switching to a supported carrier
I did not realize that Fairphone has a list of supported carriers:
The only FP5 carrier listed for Poland is “Telekom”, which is short-hand for “Deutsche Telekom”, which is simply T-Mobile.
Because as shown in the previous thread, VoLTE and VoWi-Fi didn’t work (every call I got was “unknown caller”), I simply switched my carrier from Mobile Vikings to T-Mobile (“Telekom”). Because I’m using a pre-paid plan, I needed to text “TAK” to the number 80535 to enable IMS (the stuff that makes VoLTE and VoWiFi work).
Please note that the equivalent device support list on T-Mobile’s side doesn’t list Fairphone 5 as a supported device - VoLTE i VoWiFi – wybierz najlepszą jakość połączeń| T-Mobile - even though FP5 lists T-Mobile as supported. Have fun with T-Mobile support calls if you ever need to)
Detailed diagnostics to make sure it’s now working
You can view detailed diagnostics about IMS, VoLTE and VoWi-Fi status by dialing the short code *#*#4636#*#*" in your phone app, going to “Phone information” (first option). Then, wait 2s for the three vertical dots icon to appear in the top right. Press it, and select “IMS Diagnostics”.
The first line should read “IMS Registration: Registered”. If that’s not the case, it means you need to enable IMS with your carrier (in the case of T-Mobile prepaid, text 80535 as mentioned previously). If this line doeen’t say " Registered", the below two lines about VoLTE and VoWifi eill always say unavailable. IMS is a prerequisite for VoLTE and VoWiFi to work. Being unregistered with IMS is likely a carrier issue rhather a Fairphone issue.
If you are disconnected from Wi-Fi, but connected on mobile data, “Voice over LTE” should read “Available” and “Voice over WiFi” should say “unavailable”.
If you are connected to Wi-Fi, “Voice over LTE” should be “Unavailable” and “Voice over WiFi” should read “Available”.
Calling people
When calling people though the Google “Phone” app while connected to Wi-Fi, I can see a Wi-Fi icon appearing next to the call duration, so I’m assuming VoWi-Fi is working fine.
On stock ROMs (I’m on rooted LineageOS with MindTheGapps, so doesn’t apply to me), you can see a “HD+” square icon next to the call duration in the Google Phone app when calling over VoLTE. I’m on a custom ROM so I probably could never see that icon. But I assume that it’s working since IMS is saying VoLTE is available.
Note that adding a “ims” APN wasn’t necessary, as some Pixel volte GitHub repo issues say. Adding that made my calls immediately drop.
RCS side note
Play’s (my previous carrier) implementation of RCS - the “fancy SMS” - unrelated to VoLTE or VoWifi - only works on Samsung and Huawei phones so if you want RCS to work, it may be a good idea to switch away from them too (not necessarily to T-Mobile). It also didn’t work on a stock ROM Xiaomi Redmi Note 8T, so I assume it’s not a Fairphone issue.
There’s also this very nice database showing where VoLTE and VoWi-Fi works on which phone in what Polish network (there’s an entry for FP4): https://wificalling-volte.pl/
If anyone knows a way to check whether a call is happening over VoLTE please let me know (as I can’t see the “HD+” icon in the Google Phone dialer because I’m on a custom ROM). I guess calling someone while disconnected from Wi-Fi and checking if the mobile network is at least LTE (rather than 3G) is one way? Though I’d prefer a more robust way similar to the IMS diagnostics menu.
Would be also nice to see which codec is being used for the call (EVS) to further confirm.
Disable wifi, make call and during call try if internet is working (ex. load page in webbrowser, play yt video, etc)…
Without VoLTE is not posible use internet during call.
Hi @ats , thanks for raising that.
I am with Plus and also had no idea that there is a list of officially supported carriers. Prior to purchasing FP5 I have just checked with a FP angel in Poland that Plus should be working:) and it is.
I have never encountered an issue with unknown callers but now I am wondering whether I have VoLTE and VoWi-FI enabled (I will make some calls to test it tomorrow).
It’s mentioned in my post what each line means and how to call people and check if it’s working. You are logged out of IMS so volte and wowifi probably simply don’t work. Even though you have them enabled in the settings, your SIM card doesn’t log into IMS and volte/vowifi don’t get used. IMS is a prerewuisite for volte and vowifi. As mentioned below, if using prepaid you probably need to text some special carrier number to enable it. You can just probably call Plus and tell them that your card is not logging into IMS. I’ve also seen people on the Telepolis forum just get a newer SIM card from their current carrier (and transfer their number from old sim to new sim, from same carrier to same carrier, just to get a newer generation card).
The fact that you’re not getting logged in into IMS is a carrier issue, not a Fairphone issue. The Fairphone issues start when you are logged into IMS but the hardware firmware cant handle vowifi/volte connections properly and e.g. you ge tunknown caller.
Detailed diagnostics to make sure it’s working
The first line should read “IMS Registration: Registered”. If that’s not the case, it means you need to enable IMS with your carrier (in the case of T-Mobile prepaid, text 80535 as mentioned previously
If you are disconnected from Wi-Fi, but connected on mobile data, “Voice over LTE” should read “Available” and “Voice over WiFi” should say “unavailable”.
If you are connected to Wi-Fi, “Voice over LTE” should be “Unavailable” and “Voice over WiFi” should read “Available”.
Calling people
When calling people though the Google “Phone” app while connected to Wi-Fi, I can see a Wi-Fi icon appearing next to the call duration, so I’m assuming VoWi-Fi is working fine.
On stock ROMs (I’m on rooted LineageOS with MindTheGapps, so doesn’t apply to me), you can see a “HD+” square icon next to the call duration in the Google Phone app when calling over VoLTE. I’m on a custom ROM so I probably could never see that icon. But I assume that it’s working since IMS is saying VoLTE is available.
I dont think that a wifi connection alone will disable VoLTE.
Your setting seen the screenshot above suggest you only use wifi calling when no mobile network is not available. I guess you dont see the wifi calling icon in the status bar? Change the wifi calling setting to always use wlan when connected and see if it changes
So it seems to me that with your provider, Wifi Calling does not work with the FP5, unless someone else has the same set-up and its working…is it supported in general with the prepaid SIM?
And I or lets say Fairphone disagrees here,
they will tell you its the provider to fix and properly support WifiCalling on the FP5
I have a contract on this SIM, like for years now. When I called to register VoLte they said it’s the same service as WiFi calling.
I also have a prepaid ESim with them, which I am using only for data when I run off, I could try switching for a moment and see what happens
Ok, it says I am unregistered for this prepaid eSIM . Might call again and change it. But not sure that’s gonna change much, usually contracted carriers have full spectrum of services available by default.
So I ignored the information from the plus support and sent an additional text in order to activate WiFi calling.
Apparently it worked. The status changed - now on WiFi, Volte is not available, WiFi calling available, and without WiFi the other way round, exactly as @ats mentioned.
