PagePlus notified their dealers today that the iPhone 4 and 4s are now allowed. Until now PagePlus' official policy was that iPhones were not permitted to be activated. However PagePlus has always had a kind of "don't ask, don't tell" policy around iPhones. It was possible to activate them with most PagePlus support reps as long as you just gave them your iPhone's MEID number without mentioning that it was an iPhone.
The new policy, which was confirmed by PagePlus marketing manger Denny Scher on HowardForms apparently makes iPhones "allowed but unsupported" just like other BYOP devices. The "unsupported" part just means that PagePlus doesn't guarantee that they will be able to help you with setup or network issues with a phone that wasn't sold as a PagePlus branded device.
The notice to dealers allowing the activation of iPhones explicitly states that it applies to the iPhone 4 and 4s only. Apparently iPhone 5, 5c and 5s models are still officially not allowed. But many PagePlus customers have been able to activate and use the Straight Talk version of the iPhone 5 and flashed Verizon iPhone 5, 5c and 5s models. Hopefully that won't change.