We have a PSTN telephone exchange (like Siemen's EWSD, Ascom's AXE or Alcatel's S12) and observed that it shows some strange DC offsets if the state of a connection is "waiting" or "undefined".
I wonder if this is compatible to the standards but don't know which standard is concerned. There is something in G.711 but not a definitive statement like "after dialing the switch has to send a DC offset of H00 for xy ms" or something like this.
Does anybody knows some standard concerned issues?
Thanks alot!
Regards, Peter