Hi everyone,
I want to share findings that I think are relevant to several existing reports about voice calls not working after upgrading to iodéOS 7.5 — in particular this thread about the FP4: https://community.iode.tech/t/calls-not-working-on-fp4-patch-7-5/8190/3
Important context for Switzerland: Since Sunrise shut down 3G at the end of 2025, VoLTE is no longer optional — it is the only available path for any voice call. There is no fallback. No VoLTE = no calls at all, period.
My setup:
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Pixel 7 Pro (mine) — iodéOS 7.5 — Swisscom SIM → calls work perfectly
-
Pixel 7 Pro (my daughter) — iodéOS 7.5 — TalkTalk/Sunrise SIM → no calls
-
Pixel 7a (my son) — iodéOS 7.5 — TalkTalk/Sunrise SIM → no calls
The key finding — SIM swap test:
I swapped SIM cards between devices. Results:
| Device | SIM | Calls |
|---|---|---|
| My Pixel 7 Pro | Swisscom |  Works |
| My Pixel 7 Pro | Sunrise/TalkTalk |  Broken |
| Kids’ Pixels | Swisscom | Works |
| Kids’ Pixels | Sunrise/TalkTalk | Broken |
This clearly proves:
-
It is not a device issue
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It is not a general iodéOS 7.5 issue
-
It is specifically iodéOS 7.5 + Sunrise network
Previously working: Voice calls worked perfectly on iodéOS 7.3 (or possibly 7.2 — the exact previous version needs confirmation) with the same devices and the same Sunrise SIM cards. The regression was introduced somewhere between 7.3 and 7.5.
The root cause appears to be in how iodéOS 7.5 handles the carrier config for Sunrise (MCCMNC 228 02), as MmTelFeature is never activated and no IMS registration is ever attempted over the mobile network. A detailed technical analysis has already been posted in the FP4 thread linked above.
Happy to provide logs or run any diagnostics if that helps. Thanks! 
Greetings ivi