We have a Digium TDM220 with the hardware echo cancellation module in our Asterisk system. We have two different T1 providers, one on each port of the card. Currently, we have the timing sources configured as follows:
Span 1 = Timing source 1
Span 2 = Timing source 2
Span 2 handles all of our incoming calls, while span 1 is outgoing.
The issue we are having is on some incoming calls, we are getting echo. The provider states to make sure that they are the timing source. My question is, should we do one of the following:
- Switch the timing sources, so that Span2 is timing 1, and Span 1 is timing 2?
- Set both Spans to timing 1 (this I think would cause more problems, if I understand the articles I’ve come across)
- Put Span 2 on a physically separate card.
Included below is our system.conf from /etc/dahdi/
[code]# Span 1: TE2/0/1 “T2XXP (PCI) Card 0 Span 1” (MASTER) B8ZS/ESF ClockSource
Span 2: TE2/0/2 “T2XXP (PCI) Card 0 Span 2” B8ZS/ESF
Span 3: WCT1/0 “Digium Wildcard TE110P T1/E1 Card 0”
loadzone = us
defaultzone = us[/code]
Now, I do realize that we also have specified software echo cancelers in this file, but my understanding is that if Asterisk detects the hardware module, it will not use a software canceler, if this is incorrect, please let me know.