Cisco SPA112 not dialing all numbers

Hi guys

I have a cisco SPA112 2FXS adaptor and a asterisk 11.13 +freepbx
I have the SP112 registered to asterisk and reciving calls ok

but when I connect an analog phone and dail a number only part of the digits go through (randomly)

in the SPA112 web configuration page under “voice” I can see that it only tried to dial a part of the numbers, but if I press “redial” on the analog phone it dials the whole number correctly.

I have changed the “Interdigit Short Time” to 10 but still not working even if I try to dial as fast as I can.

for example if I dial “0547678249” sometimes it will dial out “05544776778822499” and some times “5466729” and times “67249”

I suppose it has to do something with the tones that the analog phone sends to the SPA112, but I can’t get it to work.

any sort of help is very much appreciatted!