Only phonecalls not working abroad

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1

Hello everybody. I have the following problem.

I have a fairphone 4, run the latest e/os, have an odido sim card (few months old) with a proper subscription for full service abroad.

At the moment I’m in Germany, I have proper 4g network.

I can do everything exept making phonecalls. Calling via signal or whatsapp works. Browsing etc. GPS is OK. But when somebody calls me my phone does not ring and when they hang up I get a text message about a missed call.

When I make a phonecall it does not work, no tone or whatsoever.

I contacted odido, they did some resets, did not work. I checked setteingsy, selected networks, enabled/disabled calling over WiFi. Changed api.

Anybody else experiencing this problem?

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2

Resetting to factory settings also doesn’t work.

3

This sounds like the classic lack-of-VoLTE issue. Dial *#*#4636#*#* from the phone dialer, then select “Phone information.” On the following network info screen, tap the 3-dot menu in the top right corner, and see what “IMS service status” shows.

4

Thank you, just checked. I’m in my homecountry now, now calling over LTE is available. I’ll.drive over the border tomorrow andere check again. If calling doesn’t work just toggle the VoLTE slider? Or do I need to do something else, Like select more Networks in the dropdown menu. Or fiddle around with it and try

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5

Normally, you would stay connected to your provider’s APN and allow it to select its roaming partner automatically.

If you have VoLTE enabled in mobile settings, and if your provider says you should have operational VoLTE in other countries, and if the particular roaming partner is providing VoLTE service to Fairphone 4, then I don’t know. Maybe try switching VoLTE off (if there are lower networks still available in that country?).

6

There was this suggestion

7

Thank you everybody. I’ll try tomorrow. I’ll keep you posted.

8

I did a full re-install od E/Os and after that I’ve driven over the border. My IMS status was as follows:

  • Ims registration : not registered
  • Calling over LTE: not availabe
  • Calling over wifi: not available
  • Video calls: not available
  • Ut interface: available

Somehow registering on the network is not working.

I’ve tried resetting my apn settings. Unfortunately did not work.

I’ve tried downloading “carrier services” from google in the E/Os app store, did not work.

I swapped my simcard with a samsung phone with stock google android and I was able tot make a phone call. So the sim card is OK.

Meanwhile when i placed the som card from the stock android phone in my fairphone, i was unable to make phonecalls.

So the problem is or the fairphone itself or E/Os. Does somebody have any suggestions what I could try tot fix the problem?

9

So this was the response in the foreign country? and I guess the same at home?

Online search and this (random) article IMS and VoLTE: Why They’re Essential for Global Roaming in 2025 | Summa Networks suggests that Roaming will depend on IMS (at least for many carriers).

The FP4 install page includes this

Boot the stock OS at least once and check everything works — SMS, calls, and both over WiFi and LTE if available (some devices need VoLTE/VoWiFi used once on stock to provision IMS). Whatever’s broken on stock stays broken on /e/OS.

If you exhausted the permutations suggested by @Taurus, can the carrier tell you why you have failed IMS registration?

10

Hello aibd,

the response in the foreign country was:
IMS registration: not registered.

the response at home was:
IMS registration: registered.
calling over LTE: available
Calling over wifi: unavailable
videocalls : unavailable
UT-interface: available

Regarding your installation remark:I will try to install the stock android on the FP4 and check if that works.
After that I’ll probably know more.
This may take a while, but I’ll keep you guys posted.

Thank you for now and I will get back to you.

11

In this case return to Stock ROM probably cannot improve the registration; as I understand it is one off.

To loose registration in the foreign country suggests some foreign partner problem.

Interesting that you tried “Carrier services”. I expect carriers may use, depend upon or install some Google dependent SIM manager.

Success after return to Fairphone Android would ofc tend to imply carrier’s Google dependency.

12

The only reason for me to return to stock android is to check if the problem still exists. And when it does I can open a support ticket at fairphone and there can be no discussion regarding waranty etc.

In the end I want to return to E/Os again.

First I’ll try calling my carrier service line, maybe that will shed some light on the issue.

13

Good news: it works now!

I called my carrier provider, they could not see anything strange. Everything was ok according to them so they made no adjustmenst.

I flashed the latest stock android from the Fairphone website (15) to my phone (did not remove my sim card). Turned it on. After that, drove over the border and I was able to make phonecalls and send text messages.

My IMS status was:

  • Ims registration : registered
  • Calling over LTE: availabe
  • Calling over wifi: not available
  • Video calls: not available
  • Ut interface: available

I drove home. Took my simcard out of my phone and flashed the latest E/Os. Put simcard back, sSwitched it on, synchronised my account. Drove over the border and was able to make phonecalls and send text messages.

My IMS status was:

  • Ims registration : not registered
  • Calling over LTE: not availabe
  • Calling over wifi: not available
  • Video calls: not available
  • Ut interface: available

I turned off data roaming, internet, wifi and gps, forcing to call over mobile network, and this worked, also text messaging.

I really have no clue what did the trick, and if it will last and if it will work in a different country, but for now it looks good.

Looks like what aibd said: “Boot the stock OS at least once and check everything works — SMS, calls, and both over WiFi and LTE if available (some devices need VoLTE/VoWiFi used once on stock to provision IMS). Whatever’s broken on stock stays broken on /e/OS.”

Thank you all for your time and effort!

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14

Nice!

Not to rain on the parade, but… how close to your own country’s mobile towers were you, when inside Germany? :thinking:

15

Good point!

I drove until I had no service anymore and continued until the foreign service was connected. And double checked I was connected to a foreign service.

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