From: schaefer@alphanet.ch   
      
   On  23 Jan 2023 12:31:25 -0500,   
   Albert Erdmann  wrote:   
   > I am thinking about the many lines used for fire alarm and elevator   
   > emergency phones. Any idea what building owners are doing in this regard?   
      
   In Switzerland, they had to be replaced either by GSM (and 4G/5G   
   presumably, because 2G is already obsolete, and 3G will become obsolete   
   soon), or VoIP.   
      
   I heard of some cases where they still had the analog dialing devices   
   (the WSG35-2 was very popular, it was a modem that could also just dial   
   and then switch to an analog microphone). They now plugged those to the   
   ATA port of a VoIP router. As long as the dialing device uses DTMF to   
   dial, it works like a charm.   
      
   Then you just need to either ask those systems to poll the central   
   monitoring system every now and then to check they are still   
   operationnal (which most of those systems did anyway in the past   
   already).  They usually used DTMF for checking-in, which works best when   
   decoded at the ATA itself.   
      
   If they used real modem modulation, they are better off replacing the   
   modem part completely by an IP signaling or GSM system, although my   
   tests have shown that the VoIP network can still mostly work at 2400   
   bits/s with e.g. V22bis seems to still work. I could not get higher   
   speeds even with parameter tweaking and no codec conversion. I used real   
   modems on both sides: using a DSP directly attached to the VoIP network   
   might get much better results.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)