SIP connection on mobile phone - question(s)

I have a Nokia E5 on Orange contract. It is SIP enabled and I've been able to configure this to work on my home WiFi connection, but can only get incoming calls, I cannot dial out for some reason.
As it happens, that suits me as making calls over VOIP incurs a cost. I can use my normal mobile minutes or the office/home phone on whatever bundle they are on.
So far I've only used the WiFi connection. But what happens if I want to leave SIP enabled whilst I am out and about. Does that mean I would need to leave the Orange Internet connection open?
OK, I can add a data bundle to my package for £5 extra a month, but that sort of defeats the idea of being able to receive the calls without cost. Am I better just sticking to the WiFi connections at home of the office?
I like the idea of being able to give out a real phone number and my mobile ringing. I just feel a bit restricted through it only working when I'm near a wireless router.
I can also confuse people because I can give out different numbers, like Liverpool or Hull or Brighton - just for the hell of it...
It's also better for the office as they would call a proper 01/02 number and not pay for a mobile call.
No, I probably can't do everything for nothing...

Hi

Why you can receive calls but not make them is a configuration issue on the handset. From the information you have given it is impossible to be more specific than that. In my experience Nokia phones are really complicated to get the SIP stack configured. Android phones by comparison are a breeze to configure.

If you want to use SIP on the cellular network you WILL need 3G service. 2G will not cut it. Even then you probably wont get a rock solid service on 3G. You might also find that the T&C's of the mobile operator will disallow VoIP use. The operator may or may not enforce this clause by network blocks.

In essence you are much better doing VoIP over WiFi.

As an alternative there are companies that can give you a SIM card which has both a 07 number and a 01/02/03 number associated with it. This might suit your needs better. Google for the companies.

Edited by deleted (Tue 09-Aug-11 13:11:20)