Hi

Once you switched a carrier, your voicemail was reset. Old voicemail would be lost by now.

Even when switching from koodo to telus? And it’s not stored anywhere? That’s so disappointing

Telus and Koodo belong to the same company but their accounts are independently controlled. A move from one to anther is considered a normal carrier switch.

It would be highly unlikely if you switched out recently.  Even more unlikely if it was a couple of months ago (assuming under 90 days). As voicemails are only saved for 10 days normally for existing customers

https://www.koodomobile.com/en/help/voicemail