Troubles whit much extensions

Hello all.
I write my extensions.conf file, have arround 200 extensions, in the context for the sip clients have arround 70, the problem is, that when I use a eyebeam 1.3 or xlite, inmediatly call hangup.
Also ocur whit a Linksys SPA841, but in this time it can’t dial to 27 or 28 extensions in especific, when read the call hitsory these numbers appear like 0.
I try of 3CX phone whitout problems, this work perfectly.

I think that problem is of the SIP protocol parameters

If anyone knows a similar problem please quote whit your ideas.

Very thanks for all.

Sorry Bad English.