I have yet to run into any such issues. I'm not even sure it would be possible to identify that my ported number, that I've had for ... 17 years?... is prepaid.
My guess is it depends on prepaid carrier. Some of them appear as 'voip' providers. Funny thing is they have no way to detect actual carrier VOIP services like T-Mobile DIGITS as being VOIP.
If it's first party prepaid, Cricket looks the same as AT&T for example. Some carriers do stuff like buy bandwidth.com numbers, these will show up as voip even if it's only usable from a phone plan.
If it's first party prepaid, Cricket looks the same as AT&T for example. Some carriers do stuff like buy bandwidth.com numbers, these will show up as voip even if it's only usable from a phone plan.