Hey Guys - I am down under in Australia on the Vodafone Network and have had the N900 for about 5 months now..... No support from Nokia here...

I have had my sim car replaced from Vodafone a couple of times now.

Am having the same issues - Network Error, Call not Established, General Error etc when I try and make a call. A simple reboot fixes the issue, but is really annoying when you need to make a call.. Lol...

Sometimes if I make a call out then I will receive a bunch of sms that were sent hours ago and I only receive them if I make a call out.

So I don't think it would be a network issue, if I am in a different country with a different provider - Correct me if I am wrong, but I think it maybe the phone