US roaming partner is shutting down the 3G network https://www.koodomobile.com/en/help/long-distance-travel-and-roaming-prepaid

So when you traveled there, your prepaid device (which can only work on 3G network due the lack of volte) couldn't make/receive call or send/receive text.

Access to data might be also limited. I recommend you reset network settings to see if you can access to it. Koodo didn't have any tower in US so sp.koodo.com is a wrong setting

Thank you for your reply!!

How does one go about resetting their network settings? And what impact would that have when returning back to Canada?

Which phone are you using? Have you tried to restart the phone first? Depending on the device, normally a network reset is in the phone settings » general (general management)

The impact to resetting network settings is wifi and bluetooth connections are erased and need to be re-added. 

There’s an ongoing issue with roaming and calls in the US on prepaid as you need VoLTE and Koodo hasn’t enabled it yet for prepaid customers. Honestly, you can use T Mobile’s Network Pass to use their network for up to 3 months for free. It’s not a long term solution but it’ll help out for now at least as an option. 

Koodo Pre-paid roaming does not work reliably in the US because VoLTE, the newer standard in the US, is not supported by Koodo.

You will only get service if you are in a strong legacy T-Mobile signal area, such as a major airport.

Koodo should stop selling those boosters until they fix the problem on their end.

This would be a good short term solution - my mother is only travelling for the month. Does she just download this app - sign up for 3 months free - and have data she can use?

Here’s the link for their info to see how it would work. With apple it’s an esim, and I don’t recall if they’ve made it an esim as well with android yet or if it’s a wifi hub you have to get shipped still. 

T-Mobile Network Pass: Try Our 5G Network Free for 3 Months