Do you have a family or friends sim card that you can borrow?

If so put their sim card into your phone and test a phone call. Then we can determine whether it's a phone or sim issue.

Have you tried putting your SIM card into another phone to see if the same issue is occurring? If you already did and it is working fine, it is safe to say that it may be a hardware issue with your phone. Can you bring it to your local repair shop and have them assess it to see if it could be fixed?

What troubleshooting have you attempted so far? Have you tried swapping cards yet as both Allan and MilkWay suggested? Any updates?

Hey thanks for all the quick replies everyone. The phone is my (near-elderly) mother’s and is halfway across the country, so progress is… slow, to say the least.

At the moment, we’ve again confirmed that texting is fine, as well as browsing on data (and wifi for that matter).  If that sparks any new ideas for anyone, please let me know!

Thanks.

Which phone does your mother have?

Is the phones’ call volume muted?

Have you tried restarting the phone?

Knowing which phone your mother has will allow us to look for help topics or solutions that are specific to this phone. If this is an Android phone, the manufacturer and model name is usually found by going to Settings > About phone or device. 

While in a call, have your mother adjust the volume up/down buttons to a comfortable listening level to see if callers can be heard.

Restarting the phone (power off the phone, power back on) can sometimes resolve software glitches or restore/reset a setting that may have been inadvertently set.

I imagine this must be rather frustrating!  My elderly mother is half way across the city and I get strange issues from her on a fairly regular basis, and I know how hard it can be to troubleshoot these things remotely.  You’ve gotten some good suggestions so far; I would definitely start with getting her to power the phone off and back on, and adjust the volume while trying to talk with you.  Is she able to have successful conversations with anyone else (if she’s tried)?  I’m assuming you are able to speak with others just fine?  Any info you can provide us on phone model would be helpful too.

Hi again gang,

So far she’s powered off and powered on, reset, and adjusted volume in calls, to no effect yet.

She’s on a LG G5. Her region switched to VoLTE service only last year, and lost service at that time (no texting or data) but resolved it with the help of Koodo staff in store (that store, the only one in town, has since closed). The VoLTE disruption was different as she was unable to initiate or receive calls entirely, as opposed to now where she can call or be called by any number (we’ve called her and had her call numbers from several different providers), and the call can be answered, but both sides have no audio while the phones appear to have a normal call (you can still mute/volume/see the call timer tick along, but no audio for anyone).

Any other info I might be able to provide?

Thanks to everyone who’s chimed in so far.

Can you try to turn on the speaker of the phone when there was an incoming/outgoing calls? Do you have a  headphone available to plug in and see if the audio comes through? 

Also, can you put the SIM card into another phone and see of the problem follows?