[asterisk-users] WARNING[21314]: chan_zap.c:8396 pri_dchannel: Ring requested on channel 0/1 already in use on span 1. Hanging up owner.

[Steve Davies]

On 9/12/06, Steve Davies <davies147 at gmail.com> wrote:
> On 9/12/06, Giorgio Incantalupo <gincantalupo at fgasoftware.com> wrote:
> > Hi,
> > I get many of these warnings inside Asterisk log:
> > WARNING[21314]: chan_zap.c:8396 pri_dchannel: Ring requested on channel
> > 0/1 already in use on span 1.  Hanging up owner.
> >
> > What does they mean??
> >
>
> Can I assume then that 'resetinterval=never' did not make this problem go away?
>
To expand on my interest this...

We have a number of nearly identical installations of Asterisk. Same
H/W, same Zaptel, and same Asterisk build etc etc - All of the PRI
hardware is the same (Sangoma A101U), and a huge percentage of E1
lines in the UK are terminated by British Telecom.

Even though there is this amount of comonality between them, we have
exactly one customer who gets the "already in use" message seen above
on a regular basis, and a second customer who had the error only once.
The error tends to be "fatal" for inbound calls as it leaves the
channel locked permanently and the telco continues to try to use it :(

In almost every case there is an obvious SIP conversation on the box
that has not cleared down fully, and which seems to be holding the Zap
channel open in error. In the first company, they use a lot of WiFi
phones, and in the 2nd company they used to use WiFi phones (different
model), but don't anymore... I am assuming there is some kind of race
condition going on, perhaps caused by slow or unreliable SIP phone
responses to call closedown events.

I looked at the zaptel code where this message is generated, in the
hope that I could request a flush of the channel that incorrectly
shows this channel open (if the telco is trying to put a call through,
then the line is definitely meant to be clear!) but it was way beyond
my ability to understand.

I thought about Glare (someone else suggested that in another
messsage), but the telco uses lowest-free channel, and we use Zap/1G,
so use the highest free channel.

Any thoughts or input are very welcome.

Thanks
Steve