Details about configuring Snom VoIP phones

Dear Sir or Madam,

I am searching for a specific VoIP phone, and I have some questions about two Snom models before I make a purchase - the D150 and the D713.

First of all, it is widely known that encrypted VoIP traffic (i.e. SRTP) using a codec with a variable bit rate (VBR) is vulnerable to traffic analysis. The solution is to switch to a constant bit rate (CBR) codec. Thus, do the two mentioned models allow the user to configure any supported codecs (excluding G.711 for obvious reasons) into CBR mode, and, if so, which ones? I am sorry, but I do not currently own any of these models, and I do not have access to the web configuration interface to find out. The user manuals for the two models do not mention anything about CBR mode.

Second, the D713 model has a colored LCD instead of the classic monochrome one. Is it possible to completely switch off the backlight of this LCD in some way i.e. via a timeout to have the phone enter a dark mode or does the LCD stay lit all the time (including during night time)?

Third, do you have any estimates how long the two models are going to be supported regarding firmware security updates before they enter the EoS (End of sale) period?

Thank you kindly for any answers,

Thomas