Alltel and Internet Access with Treo

[MAU]

I have a Treo 650 and the service for phone, email, and Internet is with Alltel. It has taken me 6 months to finally figure out how to get my computer (MacBook Pro) to recognize my phone as wireless DUN modem. However, when it dials it tells me there is a modem error. When working on network preferences under BlueTooth Modem -- there is a dropdown list of tons of options from Verizon, to Motorolla, etc. etc. There are none listed for Alltel so which one do you use? Alltel would provide no help with the Mac.

Any ideas much appreciated.