Dear Pix, good evening!
new day brings new problem 🙂
My colleague from other region (Alcatel BSS too) has received complaint from one of our important subscribers. It’s a security firm, they have more than 300 numbers. They use GMS-modems which are located at the objects which are protected by this firm. Once per 1 hour each modem phones to server and transmits a certain tone ringing (I’m not sure I named it correctly – it’s combination of several frequencies (there is a set of such combinations, and each of them encodes a certain messages). It’s a Mesozoic solution :), but it’s our subscriber … they said that month ago they noticed problem: percentage of corrupted ringing increased from ~ 1% to ~30%. Errors appeared and disappeared spontaneously here and there without any visible interconnection. They checked and replaced modems and they also tested used protocols but without any results. After that they came to us.
Considering the fact that beginning of their problem exactly coincides with TFO activation on those BSCs, my colleagues deactivated TFO on 6 BSCs. Subscriber said that problems disappeared.
My question is: Could it be possible (even in theory) that TFO negotiation and TFO commands (which transmits within speech frames) corrupt tone ringings? Or this suggestion is unreal at all ? I don’t like the idea of deactivation TFO for third of BSCs in the region, so the answer to this question is very important to me.
Many many thanks.