Best of luck with it Ramcam. As you can see from earlier posts I have a Jasjam and have used it on both NextG and 3G. It cost me a fortune because I bought the thing outright and then still had to pay a cancellation fee to Telstra. Terrible coverage, constant phone problems (putting calls on hold for no reason, dropping out, lack of decent message notification etc). People at the other end of the phone couldn't hear my calls properly and I've had bills of nearly $200 in a month due to call drop outs or needing to call 3 or 4 times to get a decent line.
Anyway, I've given up on the thing. I've just got a Nokia 6120 which I chose because it looked smaller and simpler. It didn't cost me anything on the lowest cap plan with 3. The funny thing is it still has a calendar, notes, internet access, email, weather radar just like the Jasjam, but so far it is better as a phone and to date no dropouts at all (early days yet though). Plus it actually fits in a pocket. I haven't yet tried it with a headset.
My OH's IT manager equipped 51 people in the company with Jasjams - not one of them has a good thing to say about the phones and upper level management have all re-equipped.
PS: Anyone want to buy a slightly used Jasjam?