Sometimes when calling, no ring tone

[Totalcomsol]

We have been seeing some strange behavior lately when placing calls from the Quadro using a Broadvoice SIP trunk. Sometimes when the call is being connected you don't hear the traditinal ring tone. The call still goes through and you are abruptly connected when the other party answers. Instead of ringing all you hear is "silence". I say "silence" because it isn't completely noiseless... there is a low hiss, almost inaudible, but there. At other times calls progress just as you would expect.

Since the common denominator, as we experience this problem, is Broadvoice I was wondering if anyone else has experienced this using their service. This is a recent problem and we hadn't seen it until sometme this month. I'd also be very interested if someone has had this problem using some otehr ITSP.

[davrays]

Such situation could happen if there is a congestion in the network, or server is overloaded, and the SIP "Ringing" message has lost (or arrived together with OK message- this is also possible in case of congestion).


If Quadro receive only OK without "Ringing", it will behave exaclty that way - no ringtone,but normal call opening.


Though, of course, there may be other reasons too.


You can run some network capturing tool (e.g. Ethereal) to capture SIP packets between Quadro and Broadvoice server, and look at the arrival time of SIP messages. This will show if my assumption is correct or not.Edited by: davrays