[asterisk-users] Fax and dial-up connection issues

Tue Sep 29 06:20:27 CDT 2009

I have a pretty large setup on one of my customers. Digium TE420B (with echo cancelling module), 3 Xorcom Astribanks with 32 FXS each and 1 Xorcom Astribank with 16 FXO. These FXO ports are NOT used for fax/data transmission, as they are connected to cell phones. Not really related to the issue, but there are also 250 SIP phones.

The problem is that fax and dial-up connections are really unreliable. Faxes send and received rarely get more than 2 pages without giving a transmission error and sending garbage to the other end. Not connecting at all (and stating COMMUNICATION ERROR) is not uncommon. As of dial-up connections, of course I'm not expecting to get 33600 on that, but this customer has some dedicated systems that must dial the "mothership" and use low speeds like 9600. I also have echocancelwhenbridged=no set up on all PRI and FXS channels.

I really don't know what else I could do to solve the problem. xpp_sync is set to DAHDI so the same sync received from telco is used on the FXS ports. For the TE420, only two spans are being used today. One of them is set as the sync master (1) and all others to slaves (0). Spans 1 and 3 are connected to the telco, the others are not being used.

Follows my config files (snipped to the relevant portions, because most are really big) and some other related info. Any hints on how to solve this will be really really appreciated.

/etc/dahdi/system.conf:
loadzone=br
defaultzone=br

span=1,1,0,ccs,hdb3,crc4
bchan=1-15,17-31
hardhdlc=16

span=2,0,0,ccs,hdb3,crc4
bchan=32-46,48-62
hardhdlc=47

span=3,0,0,ccs,hdb3,crc4
bchan=63-77,79-93
hardhdlc=78

span=4,0,0,ccs,hdb3,crc4
bchan=94-108,110-124
hardhdlc=109

echocanceller=oslec,125-162
echocanceller=oslec,163-200
echocanceller=oslec,201-238
echocanceller=oslec,239-254

fxoks=125-162
fxoks=163-200
fxoks=201-238
fxsls=239-254

/etc/asterisk/chan_dahdi.conf:
[trunkgroups]

[channels]
language=pt_BR
group=1
switchtype=euroisdn
pridialplan=unknown
prilocaldialplan=unknown
priindication=outofband
signalling=pri_cpe
echocancel=yes
echocancelwhenbridged=no
relaxdtmf=no

switchtype=euroisdn
context=e1-embratel
group=1
signalling=pri_cpe
channel =>1-15,17-31

switchtype=euroisdn
context=e1-bp250
group=2
signalling=pri_net
overlapdial=yes
channel =>32-46,48-62

switchtype=euroisdn
context=e1-embratel
group=1
signalling=pri_cpe
channel => 63-77,79-91

switchtype=euroisdn
echocancel=yes
context=e1-embratel
group=3
signalling=pri_cpe
channel =>94-108,110-124

context=ddd
echocancel=256
echocancelwhenbridged=no
usecallerid=yes
cidsignalling=bell
cidstart=ring
threewaycalling=yes
callwaiting=no
transfer=yes
relaxdtmf=no
txgain=0.0
rxgain=0.0
language=pt_BR
cancallforward=yes
signalling=fxo_ks
callgroup=1
pickupgroup=1
;flash=500
;rxflash=500

;Cadencias padrao
cadence=125,125,2000,-4000
cadence=250,250,500,1000,250,250,500,-4000
cadence=125,125,125,125,125,-4000
cadence=1000,500,2500,-5000

;Chamada interna
cadence=500,300,500,3500,500,300,500,-4000

;Ring continuo
cadence=10000,1,60000,1

callerid="" <7875>
context=fax
callwaiting=no
callgroup=3
pickupgroup=3
mailbox=7875
channel => 125

/etc/asterisk/extensions.conf:
[fax]
ignorepat => 0
include => local

;Ligacoes locais
exten => _0XXXXXXXX,1,SetTransferCapability(3K1AUDIO)
exten => _0XXXXXXXX,n,Dial(DAHDI/g1/${EXTEN:1},60)

;Ligacoes DDD - telefones fixos
exten => _00XX[2-6]XXXXXXX,1,SetTransferCapability(3K1AUDIO)
exten => _00XX[2-6]XXXXXXX,n,Dial(DAHDI/g1/021${EXTEN:2},60)

# dahdi_test:
svoip01:~# dahdi_test -vv
Opened pseudo dahdi interface, measuring accuracy...

8192 samples in 8199.664 system clock sample intervals (100.094%)
8192 samples in 8198.728 system clock sample intervals (100.082%)
8192 samples in 8191.720 system clock sample intervals (99.997%)
8192 samples in 8190.992 system clock sample intervals (99.988%)
8192 samples in 8191.456 system clock sample intervals (99.993%)
8192 samples in 8191.664 system clock sample intervals (99.996%)
8192 samples in 8191.880 system clock sample intervals (99.999%)^C
--- Results after 7 passes ---
Best: 99.999 -- Worst: 99.906 -- Average: 99.970915, Difference: 100.021108

# xpp_sync:
svoip01:~# xpp_sync 
Current sync: DAHDI
Best Available Syncers:
   XBUS-01 (@usb-0000:00:1d.7-6)     [usb:0000142]  [ FXO*2 ]
   XBUS-00 (@usb-0000:00:1d.7-5)     [usb:1254]     [ FXS*4 ]
   XBUS-02 (@usb-0000:00:1d.7-3.1)   [usb:X1036520] [ FXS*4 ]
   XBUS-03 (@usb-0000:00:1d.7-3.2)   [usb:X1036521] [ FXS*4 ]
==================================================
WARNING: FXO which is not the syncer cause bad PCM
	 Affected Astribanks are:
--------------------------------------------------
	XBUS-01
==================================================

# cat /proc/interrupts 
           CPU0       CPU1       
  0:      13949          0   IO-APIC-edge      timer
  1:       4056          0   IO-APIC-edge      i8042
  8:          1          0   IO-APIC-edge      rtc0
  9:          0          0   IO-APIC-fasteoi   acpi
 14:         63          0   IO-APIC-edge      ide0
 16: 1039995212          0   IO-APIC-fasteoi   eth0, wct4xxp
 20:     172594 1269814212   IO-APIC-fasteoi   ehci_hcd:usb1, uhci_hcd:usb2
 21:          0          0   IO-APIC-fasteoi   uhci_hcd:usb3
 22:          0          0   IO-APIC-fasteoi   uhci_hcd:usb4
219:   64752376          0   PCI-MSI-edge      ioc0
NMI:          0          0   Non-maskable interrupts
LOC:  993263108  915510467   Local timer interrupts
RES:   16326632    9071480   Rescheduling interrupts
CAL:        303        529   function call interrupts
TLB:    1521462    4810165   TLB shootdowns
TRM:          0          0   Thermal event interrupts
SPU:          0          0   Spurious interrupts
ERR:          0
MIS:          0

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