We have poor phone signal in our house so wifi calling is great. Sometimes though my phone won't switch to it and tries to use the mobile network. This results in dropped calls and poor call quality. It's really frustrating when I know there is a strong and reliable wifi connection available.
Is there a way to force WiFi calling on the Oppo A15?
Best answer by WelshPaul
WiFi calling is for when you have poor to no signal and no there is no phone that will over ride this. 😔
However, on my Samsung S21 Ultra if I put the phone into airplane mode and then enable WiFi I remain connect to WiFi calling permanently. 
+24WiFi calling is for when you have poor to no signal and no there is no phone that will over ride this. 😔
However, on my Samsung S21 Ultra if I put the phone into airplane mode and then enable WiFi I remain connect to WiFi calling permanently.
Thanks. I did try that on the Oppo, but it wouldn't let me make a call when Aeroplane mode was on 😞
+24Just tested and confirmed that it works on my sons Oppo Reno4 Z too.
(device was purchased sim free running Android 11 / ColorOS V11.1)
It’s possible that you require Android 11 for this work around to errr work. I think the Oppo A15 runs Android 10 / ColorOS V7.1? Not 100% sure but it looks like the Oppo A15 will get an upgrade to Android 11 according to this article: https://www.getdroidtips.com/oppo-a15-and-a15s-android-11-coloros-11-update-tracker/
It’s working now… I can turn on Airplane mode, then turn on WiFi, and then route all calls over WiFi. Thanks for all your help!
Hmm, annoyingly it’s decided not to work today. It’s running android 10 / ColorOS 7.2. So frustrating!
+24When you say it’s decided not to work today, what do you mean exactly?
There appears to be several posts this morning regarding WiFi calling not working and so there could be an issue with WiFi calling on the network this morning.
Ahh ok, yes I did the whole turn on airplane mode, then turn on wifi, then wait… but no wifi calling logo popped up. So when I went to make a call, it told me I had to turn off Airplane mode. Good to know it could be a general, temporary issue.
Thanks 
Hope ID update /add more phones to wifi calling / 4G calling soon.
Received ID contract sim this morning but will be ringing later today to cancel as wifi calling / 4g calling does not work on 3 phones in household including oneplus 8 pro and realme x50 pro.
can’t get wifi calling working on my Galaxy S10e. It’s set up correctly, Curry’s confirmed that. Samsung are telling me its the network provider and idmobile are telling me its the phone.
The phone will not allow me to make a call with Flight Mode enabled even with my wifi enabled, so can’t test it out that way. I have never seen the wifi calling symbol at the top of the display
Any ideas anybody?
+24Have you got the latest software installed?
Have you tried placing the handset into flight mode and then enabling Wi-fi only.
It can sometimes take a few minutes for the Wi-fi calling to show.
Kash
+24can’t get wifi calling working on my Galaxy S10e. It’s set up correctly, Curry’s confirmed that. Samsung are telling me its the network provider and idmobile are telling me its the phone.
The phone will not allow me to make a call with Flight Mode enabled even with my wifi enabled, so can’t test it out that way. I have never seen the wifi calling symbol at the top of the display
Any ideas anybody?
Is the handset an unlocked UK model? Where did you get it?
My Galaxy S10e is a “unlocked renewed model” purchased on Amazon.
I’ve just discovered it has a CSC code of XAA which is USA
Would this cause the wifi-calling not to work.
+24Would this cause the wifi-calling not to work.
Yes.
WelshPaul
you seem pretty sure, any explanation why, I want to be certain if I’m going to return the phone
+24I could write a long and rather technical post but as I'm using my phone to write this post, I will save my sanity. Have a read of the thread linked to below:
https://community.idmobile.co.uk/device-phone-support-26/wifi-calling-not-working-on-a52s-45798
Thanks WelshPaul
If I can’t return it, I’ll try and work up some courage to get it reflashed. Any thoughts that?
+24Normally I would recommend that you change the CSC to “BTU” (this method might require a factory reset too), but your phone is a US model right? so, I cannot guarantee it will work even if you change the CSC because US models usually utilise different hardware compared to European models.
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