ERROR[10771] chan_dahdi.c: PRI Span: 3 XXX Invalid Progress

Hello guys!
I’ve got 4 E1 in my Asterisk NOW 2.0.2. I use 2 Digium TE220B. E1 DAHDI/i1 and E1 DAHDI/i3 is connected to PSTN, E1 DAHDI/i2 and E1 DAHDI/i4 is connected to my internal PBX. All calls from my internal PBX flow through Asterisk to PSTN. From time to time I see this error in CLI. It happens, when someone calls from inside to outside. This is log:
[2012-10-04 13:58:47] VERBOSE[7172] app_dial.c: – DAHDI/i3/1111111-684 is proceeding passing it to DAHDI/i4/139-6e5
[2012-10-04 13:58:48] ERROR[10771] chan_dahdi.c: PRI Span: 3 XXX Invalid Progress indicator value received: 09
[2012-10-04 13:58:48] VERBOSE[7172] app_dial.c: – DAHDI/i3/1111111-684 is ringing

I’ve replaced the original number to 1111111. It’s interesting, that this ERROR doesn’t interrupt the call. Everything seems works fine! But what is it? I just want to investigate, what it can be. Unfortunatly, I haven’t found something in Google.

Please, help me with it.
Thank you!

It’s OK, guys! Nothing to worry about!
freepbx.org/forum/freepbx/ge … tor-value-