Question about prepaid $100/360 days. ZTE Cymbal 2 phone has 4G technology? Top up with cards or credit card if you use up the 400 minutes before the year is over?

Hello, 

My elderly father currently uses Speakout wireless, however it sounds like they are getting rid of the 3G network. He currently uses a flip phone with 3G technology.

I’m guessing he would have to upgrade to Koodo’s ZTE Cymbal 2 for 4G? He prefers using a flip phone.

He currently pays around $100 a year with Speakout so we are considering the $100/360 day Koodo plan.

Questions: If he runs out of 400 minutes before the year is finished, does he have to spend another $100 or can he purchase top up amounts of $25, $50 etc?

Thank you for your help!