Sprint has turned on what is known as Modem NAI, a new tethering monitoring system in almost all Power Vision devices that will ensure that Power Vision phones have the required Phone-As-Modem plan to be able to connect to the internet. This includes the Sanyo MM-9000, Samsung MM-A900, MM-A920, and MM-A940. The only exception to this rule is the PPC-6700, which does not support Modem NAI, and will continue to be able to tether without a PAM plan.
Customers who attempt to tether on an EV-DO phone without a PAM plan will receive either no error or an authentication failure message on their phone. Hackers on many sites have posted, and confirmed that there is an existing method on EV-DO Samsung phones to disable Modem NAI, for which Sprint PCS Info is currently providing coverage of.
Existing Vision devices will continue to be able to tether without a PAM plan, though Sprint encourages those customers to sign up for a PAM plan.