What phone do you have?

Try enabling VoLTE on your phone.

https://www.koodomobile.com/en/help/volte?srsltid=AfmBOorP-LZkWuSwZc184B_YjZkLLiUuZmYmUKSAqnmHVh4s5A3uh8QR

Also have you restarted your phone?  What city are you in where your 3G went down?

Xiaomi, Redmi note 10 pro. It's already enabled.

Koodo may not always support VoLTE on non-North American phones.

Have you restarted your phone to see if 3G can connect?

If you change your network settings to 3G Only, are you able to connect to the network?

Yes, restarted nothing, I changed in 3g only I got no network. Idk what's happening 

Was your phone able to connect to 3G before?

What city are you in?

Yes everything was fine until last week. I'm in Ottawa in Ontario 

I’m not seeing any outages in Ottawa right now.

https://www.telus.com/en/on/outages

Did you update your phone recently?

If you login to your self serve, do you see VoLTE as part of your Add-ons in the plans page?

No updates are available, I did the last update. When I go self-serve, my plan is 4G network, includes unlimited calls and texts and 50GB of data.

When did you do the last update?  Did the update happen and then this issue started?

Under the Add-ons section.  What add-ons do you see?

I did it 1 year ago... No everything was fine after the update until the last week.

Under the Add-ons section.  What add-ons do you see?

Unlimited International SMS and MMS

Unlimited LD Pack (27 countries)

Let me flag a rep for you

Okay thank you 

If you already changed to 3G and it didn’t have signal, your phone couldn’t have the ability to call any more as VoLTE wasn’t never supported on any Xiaomi device. There isn’t much Koodo would do. 
I would recommend you to change your device as 3G network is being phased out. You would see less and less 3G network available (and you couldn’t make/receive call)

So buy a new phone?

That is your decision to make. As of now, if you would like to use VoLTE on Koodo network, you would have to use a compatible device as stated in this link https://www.koodomobile.com/en/help/volte

Everything was fine until last week... So disappointed 

I saw many reports recently about the non-availability of 3g network. It appears the 3G shutdown has begun in urban area. 

Wanna buy another Xiaomi but most recent (mi 11 ultra) you think everything will working well?. Thanks 

I wouldn’t recommend it. You will have the same issue that you currently have.

You should buy device that was destined for Canadian market and is validated with Koodo network. Check out the link I posted above

I checked, not a lot of brands... but it's okay thanks you for your help I'll change my phone asap