What phone do you have Jeremy? Do you have minutes left on a talk booster? Also have you tried going into 'call' which is located in your phone settings to see if anything weird was selected? Sorry for all the questions :P
I have a old phone Samsung galaxy captivate, I just start using Koodo prepaid services, the data and message is fine. I do have 500 minutes booster and it is charging my minutes which I can see from my call history.
I tired speaker phone too but no luck.
I called technical support and they ask me to bring to store to have a look. But the sales just told me to change my phone when she tired call once with no sound.