I just installed the 4.2 beta "App Image" version of Linphone on my Linux Mint Desktop with the hope that I might actually be able to make calls with it from my personal, Xeloq, SIP account. The account will register but I have never been able to make a call. It is amusing to see all of the highly detailed technical questions being posted here and I can sympathize with the users because I have never been able to get the blinking thing to work at all.