those of you that use betamax (voipbuster, voipstunt, nonoh and the hundred rest), you know that if you register a valid phone no (you mobile for eg!) with your betamax service, u can set the voip application to send a caller id info so that the recipient of your call sees your mobile no calling, not some strange numbers or privte no. the setting for that was "public user name" on the symbian phones it is "address" on n900's sip settings give it a try!