Skype is slipping from the grips of its current owner eBay but that's not the only big news from the VOIP service - it's planning a platform to allow third party apps to make Skype calls.
OpenSky is a free service provided by Gizmo5 which allows any mobile phone, web browser or IP aware phone network (SIP, asterisk, etc) to communicate with Skype users. OpenSky supports sending text messages and voice calls.