Seriously bad jitter problems on e1/t1 interface (digium)

Hi. I have a digium pri/e1/t1 card (wcte12xp0). I have a site that has about 93 users.

The site was running fine until recently when it got overwhelmed with jitter problems. I cant make a call on the pri/t1/e1 line without experiencing numerous breaks in the conversation.

Also in /etc/asterisk/zapata.conf there is the following line

; Configure jitter buffers in zapata (each one is 20ms, default is 4)
;
jitterbuffers=4

Could this be part of my problem that I am having. How do I increase the size of my jitterbuffer and If I say jitterbuffers=40, will that mean that I have jitter buffers available for 40 channels?

Kindest Regards

TJMA

oh ps zttest shows a 99.99% average