Truphone is a new entrant in the VOIP segment for mobile phones. Truphone offers a free VOIP client for Nokia E-Series (E60,E61,E70) and is offering free landline calls till December 2006. Clients for Nokia N-Series like N70, N80, N90, N91, N92 and N93 will be available at a later date.
UK and US will get Truphone numbers appropriate to their countries (i.e. +44 and +1 respectively). These users will be able to make and receive calls on their Truphone numbers just like a traditional mobile/cell phone.
There’s also a tutorial on their site showing how to configure the software for use via WLAN