Mobile telephony has an important role in our modern world. VoIP would fail if it stayed wired. Most VoIP users are now scrutinizing the pipeline for services that will allow them to conveniently make free or cheap calls using their mobile phones, anywhere. A few mobile VoIP services have emerged, pioneering into a promising industry.
You could call through VoIP on your mobile phone just like you would on a PC, but through a wireless network. So, basically it can be as free as with software based VoIP service, as long as you call people using the same service on their PC or mobile phone. But your cost will not always be nil since you need connection through a wireless service - a data plan (which is not free, in most places). WiFi can be free in hotspots or at home - if you have a wireless router showering your house with Internet connection from your ADSL line. But then still, you need to have a mobile phone that has WiFi connectivity.
Anyone that has a need for mobile telephony (who hasn't?), and who wants to cut down the cost of this expensive way of communication. It can prove to be more profitable for heavy mobile users like business people and travelers.
- All the pros of software-based services: Free, available worldwide, features, etc.
- Portability.
- The need of a data plan or a wireless network, to connect your mobile device to the Internet
- Mobile VoIP services are not compatible with all mobile models.
- Call quality is not always very good, due to the wireless carriers.

