First : Install nimbuzz messanger in your Mobile or PC.
www.nimbuzz.com or get.nimbuzz.com on your mobile
Note: Also you can use nimbuzz as a IM or talk
Second: Register with any SIP provider
I choose nymgo and you dont have a topup card yo can use Sipgate as it free. You choose any of them they will supply you all the sip settings when you register which you will need for nimbuzz.
Third: Set up SIP in Nimbuzz.
Open nimbuzz , login with your nimbuzz id, then open settings/call settings/Sip provider and select nymgo ( or other) Enter the settings for the sip provider for nymgo you just need your user name and password and sip proxy server settings and slect save. After that nimbuzz will show your Sip Provider status should changes to active
