If you already have Fring, use the below settings to connect via aircelvoice:
Fring SIP settings and voip setup configuration guide:
Choose SIP from the list (press your joystick in to select items in the list) and press Next using your right soft key.
A new screen appears choose "Other" from the list.
User ID
Password
SIP proxy
your aircelvoice username*
your aircelvoice account password *
sip.aircelvoice.com
* Your existing aircelvoice username and password
Once Fring is registered to make a SIP call:
1. Choose a contact in your address book and press "Options" using your left soft key.
2. From the Call submenu, choose "SIP call". Your call is made using the aircelvoice account you have added.