
As advertised, Babble does require ISDN/broadband connections to work and will not operate on even the fastest dial-up connection. Registration is free, the software download is free and there is no obligation to subscribe whatsoever. Voicemail and instant messaging are also free. It doesn't, however, have some of the more sophisticated Skype features like video and conference calling.
So why am I flirting with Babble? Because Babble uses an industry-wide standard called SIP (Session Initiation Protocol), and it may be able to work (not tried yet) on Nokia N80 which has just become SIP compliant.