[asterisk-users] Problem with "AT&T Maintenance" protocol in PRI connection, no B+D channels available

Matthew Fredrickson creslin at digium.com
Tue Mar 20 15:38:16 MST 2007


I've never seen a PRI dchannel on a T1 on a timeslot other than the  
24th.  Are you sure that it's really on channel 23?

Matthew Fredrickson

On Mar 20, 2007, at 8:54 AM, Kanelbullar wrote:

> Thanks for your answer, Bruno. However, the configuration you provided  
> is for an E1 connection and we are using a T1, having channel 23 as D  
> channel.
>
> Bruno De Luca <bdeluca at fgasoftware.com> escreveu:d-channel is in midle
>>
>> bchan=1-15,17-31
>> dchan=16
>> loadzone = it
>> defaultzone = it
>>
>>
>>
>>
>> Kanelbullar wrote:Hi guys,
>>>  
>>> We are experiencing a problem with a T1 PRI connection. After trying  
>>> a number of variations in the configuration files, the behavior is  
>>> always the same: no B channels come up and the D channel doesn't  
>>> appear to be working well. We can see there are AT&T Maintenance  
>>> messages being exchanged by asterisk and the provider, CONNECT and  
>>> CONNECT ACKNOWLEDGE, but that doesn't appear to be enough to bring  
>>> the D and B channels properly up. Are there any messages missing?  
>>> When we attempt to make a call, we can see the Q.931 SETUP message  
>>> being sent. But shortly after we are getting a LAPD DISC message,  
>>> which ends up originating a Q.931 DISCONNECT message, terminating  
>>> the call.
>>>  
>>> What could be the problem here?
>>> 	• 	Could there be any configuration issue on our side?
>>> 	• 	Does libpri provide complete support to the AT&T Maintenance  
>>> protocol or could this connection be incompatible?
>>>  
>>> Any help would be highly appreciated.
>>>  
>>> Many thanks in advance,
>>> Paulo
>>>  
>>> ----------------------------------------------------------------
>>> PS: Configuration files, messages and pri debug snippets follow
>>>  
>>> zaptel.conf
>>> ----------------
>>> loadzone = us
>>> defaultzone=us
>>> #Span 1: TE2/0/1 "T2XXP (PCI) Card 0 Span 1"  PRI_T1
>>> span=1,0,0,esf,b8zs,crc4
>>> bchan=1-23
>>> dchan=24
>>>  
>>> zapata.conf
>>> ----------------
>>> [channels]
>>> group = 0
>>> usecallingpres = yes
>>> switchtype = national
>>> context = inbound
>>> signalling = pri_cpe
>>> usecallerid = yes
>>> channel = 1-23
>>>
>>> messages
>>> --------------
>>> Mar 19 15:32:23 NOTICE[3306] cdr.c: CDR logging disabled, data will  
>>> be lost.
>>> Mar 19 15:32:23 WARNING[3306] pbx_ael.c: Unable to open  
>>> '/etc/asterisk/extensions.ael': No such file or directory
>>> Mar 19 15:32:23 WARNING[3306] pbx.c: Requested contexts didn't get  
>>> merged
>>> Mar 19 15:33:17 WARNING[3322] chan_zap.c: No D-channels available!   
>>> Using Primary channel 24 as D-channel anyway!
>>> Mar 19 15:33:58 WARNING[3322] chan_zap.c: No D-channels available!   
>>> Using Primary channel 24 as D-channel anyway!
>>> Mar 19 15:33:58 WARNING[3366] app_dial.c: Unable to forward voice
>>> [...]
>>>  
>>> pri debug span
>>> ----------------------
>>> > [ 00 01 0a 0a 03 01 00 07 01 01 c0 18 01 ac ]
>>> > Informational frame:
>>> > SAPI: 00  C/R: 0 EA: 0
>>> >  TEI: 000        EA: 1
>>> > N(S): 005   0: 0
>>> > N(R): 005   P: 0
>>> > 10 bytes of data
>>> -- Restarting T203 counter
>>> Stopping T_203 timer
>>> Starting T_200 timer
>>> > Protocol Discriminator: AT&T Maintenance (3)  len=10
>>> > Call Ref: len= 1 (reference 0/0x0) (Originator)
>>> > Message type: CONNECT (7)
>>> > [01 01 c0]
>>> > IE: Change Status (len = 3)
>>> > [18 01 ac]
>>> > Channel ID (len= 3) [ Ext: 1  IntID: Implicit, PRI Spare: 0,  
>>> Exclusive Dchan: 1
>>> >                        ChanSel: As indicated in following octets
>>>                          ]
>>> (...)
>>> < [ 02 01 0a 0c 03 01 00 0f 01 01 c0 18 01 ac ]
>>> < Informational frame:
>>> < SAPI: 00  C/R: 1 EA: 0
>>> <  TEI: 000        EA: 1
>>> < N(S): 005   0: 0
>>> < N(R): 006   P: 0
>>> < 10 bytes of data
>>> -- ACKing all packets from 5 to (but not including) 6
>>> -- Since there was nothing left, stopping T200 counter
>>> -- Stopping T203 counter since we got an ACK
>>> -- Nothing left, starting T203 counter
>>> < Protocol Discriminator: AT&T Maintenance (3)  len=10
>>> < Call Ref: len= 1 (reference 0/0x0) (Originator)
>>> < Message type: CONNECT ACKNOWLEDGE (15)
>>> < [01 01 c0]
>>> < IE: Change Status (len = 3)
>>> < [18 01 ac]
>>> < Channel ID (len= 3) [ Ext: 1  IntID: Implicit, PRI Spare: 0,  
>>> Exclusive Dchan: 1
>>> <                        ChanSel: As indicated in following octets
>>>                          ]
>>> (...)
>>> > Protocol Discriminator: Q.931 (8)  len=40
>>> > Call Ref: len= 2 (reference 2/0x2) (Originator)
>>> > Message type: SETUP (5)
>>> > [04 03 80 90 a2]
>>> > Bearer Capability (len= 5) [ Ext: 1  Q.931 Std: 0  Info transfer  
>>> capability: Speech (0)
>>> >                              Ext: 1  Trans mode/rate: 64kbps,  
>>> circuit-mode (16)
>>> >                              Ext: 1  User information layer 1:  
>>> u-Law (34)
>>> > [18 03 a9 83 82]
>>> > Channel ID (len= 5) [ Ext: 1  IntID: Implicit, PRI Spare: 0,  
>>> Exclusive Dchan: 0
>>> >                        ChanSel: Reserved
>>> >                       Ext: 1  Coding: 0   Number Specified    
>>> Channel Type: 3
>>> >                       Ext: 1  Channel: 2 ]
>>> > [1e 02 80 83]
>>> > Progress Indicator (len= 4) [ Ext: 1  Coding: CCITT (ITU) standard  
>>> (0) 0: 0   Location: User (0)
>>> >                               Ext: 1  Progress Description:  
>>> Calling equipment is non-ISDN. (3) ]
>>> > [6c 06 21 80 37 31 30 30]
>>> > Calling Number (len= 8) [ Ext: 0  TON: National Number (2)  NPI:  
>>> ISDN/Telephony Numbering Plan (E.164/E.163) (1)
>>> >                           Presentation: Presentation permitted,  
>>> user number not screened (0) '7100' ]
>>> > [70 0b a1 35 38 35 34 31 39 37 39 39 35]
>>> > Called Number (len=13) [ Ext: 1  TON: National Number (2)  NPI:  
>>> ISDN/Telephony Numbering Plan (E.164/E.163) (1) '5854197995' ]
>>> (...)
>>> < [ 02 01 53 ]
>>> < Unnumbered frame:
>>> < SAPI: 00  C/R: 1 EA: 0
>>> <  TEI: 000        EA: 1
>>> <   M3: 2   P/F: 1 M2: 0 11: 3  [ DISC (disconnect) ]
>>> < 0 bytes of data
>>> -- Got Disconnect from peer.
>>> Sending Unnumbered Acknowledgement
>>> > [ 02 01 73 ]
>>> > Unnumbered frame:
>>> > SAPI: 00  C/R: 1 EA: 0
>>> >  TEI: 000        EA: 1
>>> >   M3: 3   P/F: 1 M2: 0 11: 3  [ UA (unnumbered acknowledgement) ]
>>> > 0 bytes of data
>>> -- Restarting T203 counter
>>> > [ 00 01 00 00 08 02 00 02 45 08 02 81 90 ]
>>> > Informational frame:
>>> > SAPI: 00  C/R: 0 EA: 0
>>> >  TEI: 000        EA: 1
>>> > N(S): 000   0: 0
>>> > N(R): 000   P: 0
>>> > 9 bytes of data
>>> Starting T_200 timer
>>> > Protocol Discriminator: Q.931 (8)  len=9
>>> > Call Ref: len= 2 (reference 2/0x2) (Originator)
>>> > Message type: DISCONNECT (69)
>>> > [08 02 81 90]
>>> > Cause (len= 4) [ Ext: 1  Coding: CCITT (ITU) standard (0) 0: 0    
>>> Location: Private network serving the local user (1)
>>> >                  Ext: 1  Cause: Unknown (16), class = Normal Event  
>>> (1) ]
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