Help! I cannot connect to the internet or check my email, using my Palm Zire 72 and my Siemens S56 phone.

I have set up a bluetooth connection between my phone and Z72, and they will talk and send things back and forth. And I have gone through the phone set up for connecting to the internet - chosen Cingular GPRS service, USA, and my phone. But when I actually hit Connect, I get a message: "Error: PPP timeout (0x1231). I'm guessing this is a problem with either my network setup, or with Cingular itself. I *can* check the internet and my email on my phone, so I know it should be able to do this. But I want to check the internet and email on my PDA now... Do I need to put in a phone number or ISP somewhere on the Z72 so it'll know to dial into my ISP? (I use Netzero).

Thanks so much!