Well Moon77, this forum is supposed to be for -and also by- users helping each other out. Generally you will find that both the Admins and users are helpful and knowledgable. Please be considerate in your questions and answers, because some of the previous posts can come across as blunt.
(2) If you are looking for ways to hide your internet footprint, I'm sure a Raspberry or Linux with Asterisk also allows you to spoof the MAC address, isolate the phone from the internet and monitor all network traffic.
(3) Yealink has been forthcoming with the information you requested, but it is up to you to believe/accept the response as valid. By asking if there is a backdoor in the software, I'm not sure what kind of response you expected, from any vendor for that matter.
(4) Eventhough the implementation is based on Linux, Yealink has the right to keep the rest of their implementation closed. The phones are not advertised as having open hardware or software... So you can ask, but please don't expect Yealink will change their business model solely on that request.
(7) Heartbleed Advisory can be found in
this thread.
(8) You can find the sources of the opensource packages online at
http://www.yealink.com/GPLOpenSource.aspx
While safe VOIP communications is always a consideration, I don't believe the Yealink phones are inherently less secure then any other brand. While the phones/software is not perfect, the support team do listen to the users and accept input for future versions.
