How to troubleshooting

Hi Everybody

I have set up an Asterisk on my Linux box to server my friends. The system setup is similar as a calling card service. Everything seems running fine except two issues which I don’t know where I should look into.

One of my users complains that one of his destination numbers almost never got answered. He can hear the ring after he dial the destination number, but at other end there is no ring at all.

Second, a user complained he heard a tying sound in the background.

So something like these where I should look into. My setting is a normal calling sever layout. Caller – PSTN – DID Provider –- My Asterisk – Termination Provider – Destination

Also can you suggest me a good book or website I can learn VoIP, SIP and Asterisk?


Unless your dialplan is explicitly calling “Ringing()”, your problem lies with the termination provider, or downstream of them.

I have no idea what a tying sound is. Tying is something one does with knots, and it is usually pretty silent.

Thanks David

I have another very basic question for VoIP. After two parties start talk, how does the voice flow? Which components get involved in voice flow? My system looks like following if I understanding is correct. So my question is after two start talking, are DID Provider and Termination Provider still in the picture? Does the digitalized voice stream still flow though DID provider, My Asterisk Box and Termination Provider?

Person<–>PSTN<–>DID Provider<–>My Asterisk Box<–>Termination Provider<–>PSTN<–>Person

Thank you very much!

It depends on the configuration. In your example, it is almost certain that all of them carry the speech. Asterisk can be configured so that Asterisk is bypassed, if certain conditions are met. One of those is that the upstream and downstream support it. Commercial SIP service providers generally don’t support it.

It is also possible to transfer a SIP call, but that is not well known and well supported in Asterisk. Again, I would expect your SIP service providers to reject attempts to do that.