[asterisk-ss7] Didum Octal span card

Gregory Massel greg at csurf.co.za
Thu Dec 12 05:17:35 CST 2013

I have had ongoing problems with the VPMOCT256 modules on these cards 
that Digium has not been able to resolve as yet. This has occurred in 
multiple sites using a number of different cards, so it's definitely not 
a case of just one faulty unit. The VPMOCT256 will intermittently cause 
dead-silence in one direction of the audio path.

My suggestion is the either use 2x quad-port cards (with a timing cable 
if need be), or, get the TE820F (i.e. the octal span without hardware 
echo cancellation), or, if you do use the TE820BF, disable the hardware 
echo cancellation by adding the following to /etc/modprobe.d/dahdi.conf:
options wct4xxp vpmdtmfsupport=0 vpmsupport=0

Note that the octal span card itself (TE820F) works absolutely fine with 
libss7, even under high volume. I use these both paired (for 16 E1 spans 
per server) or coupled with TE420's (for 12 E1 spans per server).

The only issue is the VPM module.

On 2013/12/12 12:50 PM, Antoine Megalla wrote:
> Hi,
> I have a new SS7 installation where the client wants to connect 8 E1s 
> to the PSTN switch.
> I was wondering of the Digium octal span card (TE820BF) was tested in 
> successful SS7 installation and if so was that installation using 
> libss7 or chan_ss7.
> Thank you for you help.
> Regards,
> Antoine Megalla

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