I´m using openSUSE 12.3 and just wanted to configure Linphone 3.6.1 but I cannot complete the setup wizard. When I put in my username, password and SIP domain name, I cannot push the apply button... I don´t know, what is wrong there. But, I use it successfully with Android. You can enable there SRTP and TLS transport to your SIP server. You need a SIP server / provider that offers TLS encrypted transport! Without such a server you cannot use SRTP/ZRTP! Sipgate for example, does not offer TLS. Dus.net offers TLS for SIP, but my impression is, you need to buy a full service there. No clue, if you can get a SIP server only. Additionally, I suppose, Linphone does not fully comply with the SIP standard. The SIP standard says, a SIP client should be able to act as a server and client to be able to establish a direct client to client connection. I´m not sure, but I think Linphone does not allow direct client to client connections. I have not found yet a SIP provider that offers encryption. And to be honest, I have doubt, if the ones who do are really trustworthy. If in doubt, they will give their keys to the government. Thus I play with the thought to build my own SIP server. Malte