Swap sim cards with someone and see if the problem follows.

I’ve had my iPhone 10XR for 3 years and it started to do that recently. It lasted fir over a week until I powered my phone off and in.  Resolved. The Koodo Support site suggests that in the situation where your phone behaves oddly one or more of the following sometimes resolve the issue:

Power off and on.  

Update operating system.  

Power off, remove SIM card and then put it back in,.  

Power off, remove battery (if battery is removable) then put battery back in. 

@NicoleV Swapping SIM with one from another provider is a good idea, but could be tricky to test for an extended period when your friends will want their SIM back. Or maybe you have another phone you can temporarily try your own SIM in too to help rule out the service...

Here are a few more easier things I recommend doing to help narrow down the source…

• Place test calls to this echo-test number: +1 226 244 4444 - It will repeat back whatever it hears from you. This will allow you to see if you have two-way audio without needing to involve someone else.
• Test calls using alternate audio paths to rule out a problem with the earpiece, ie: Speakerphone, Wired earphones/headset via 3.5mm jack adapter etc, wireless via Bluetooth. If you encounter dropouts, try switching between these during the same call.
• Test calls with a free Wi-Fi calling app to see if the problem persists on calls that don’t use your Koodo service too. Two highly regarded apps are Fongo Mobile, and TextNow. Both will give you a second Canadian number to use. You can also use the previously noted echo-test number with these apps as well.

Good luck! Looking forward to hear the results of your tests.

An Apple technician already did the turn phone off, take out SIM card, take out battery, etc on my phone. He said there was nothing wrong with my phone. 

I was in touch with Koodo and the technician I spoke to had me try different things and in the end figured out that I have to speak to a more advanced Koodo technician.

But I will try using my  What’sApp  wifi calling with my family which is a different Service Provider and which should help me.  Good idea! Thanks!

Id still try what GOran is suggesting.  Try a family or friends sim in your phone and try your sim in your family or friend’s phone and see if the issue still happens.  DOes the issue follow your sim or does it follow your phone.

@NicoleV

And also still try speakerphone and an external headset / bluetooth too.

I did try speakerphone and it cut out the same. 

I’m working with a Koodo technician now and we’re first trying my phone on wifi only (I have a different provider) when I’m at home where it happens a lot (I can hear the person on the other phone clearly but they can’t hear me or I cut in and out).

That should help to see whether it’s Koodo or my Iphone causing the problem.

@NicoleV How about data-only calls using apps like Whatsapp, facebook messenger, etc?

Could also be interesting to try disabling VoLTE (you may not have the option anymore) or disabling LTE / forcing 3G mode (aka HSPA or WCDMA) to see if that improves call quality at all.

Remember try the echo test number 226 244 4444 which will quickly let you hear your own audio repeated back to you.