How do I activate an iPhone 3Gs without iTunes or WiFi? Is it possible to activate and use my iPhone 3Gs (A1303) without using iTunes?

I think it is important, not to connect it to a WiFi cause I don't want to update it in any way.

When I connect to a working WiFi and continue the activation process, it says:


  Your iPhone could not be activated because the activation server is temporarily unavailable. Try connecting your iPhone to iTunes to activate it, or try again in a couple of minutes.
  
  If this problem persists, contact Apple Support at apple.com/support


No matter, where and when I try that, it is the same message since months :)

When I connect it via iTunes, iTunes complains that there ought to be no SIM card in it.

So maybe it is better to find out to How do I jailbreak an iphone 3gs without activating it?
The only way you can activate your iPhone is using a sim-card. You don't have to connect to iTunes or WiFi.

It will show you alerts whether you want to upgrade or not, you can simply decline these.