A direct node-to-node chat framework is coming to Web browsers pretty soon, obviating the need for spyware like Skype or Google's alternatives. SIP is fine, but network effect is an issue and some networks seem to be impeding SIP, especially for mobile. I have experimented a lot with SIP clients because secret services are reportedly eavesdropping on more and more calls, with voice recognition too. I put many links about it in this Web site but I rarely write full articles on the matter because it's not my focus. Anyway, there is this new report which confirms warrantless wiretapping of Skype calls by secret services:
Russian intelligence agencies can not only listen to your conversations, but also determine your location.
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"Special services have been capable for several years not only to wiretap but also to locate a Skype user. That's why, for instance, employees of our company are forbidden to discuss business-related topics on Skype," General Director of Group-IB, Ilya Sachkov,” says to Vedomosti.
“After Microsoft acquired Skype in May 2011, it updated the software with technology allowing legitimate wiretapping,” says Maksim Emm, Director of Peak Systems.