If SKYPE would create an open API to make and receive calls, SKYPE could be leveraged across companies networks via IP PBX's, resulting in more revenue for SKYPE and better coverage for SKYPE users.Pretty much the whole VOIP industry is now adhering to the SIP standard in an effort to inter-operate, yet SKYPE refuses to communicate with anyone. There is no need to open source code, but refusing interoperability and seeking to create a monopoly by locking its users in is detrimental to SKYPE users and to the VOIP industry.
As a result, the SKYPE train seems to be coming to a halt. According to various blog sites - its growth has slowed down rapidly. Then there was an embarrassing multi-day outage this summer for which no adequate reason was posted. Recently, its founder and CEO resigned.
The writing is on the wall - just like any other proprietary vendor that refused to inter-operate - SKYPE will fade away. Open up, SKYPE!