Hi i have a number of D862 handsets along with M70 and M900's

Im planing to install on to a Panasonic Ns700 pbx.

Ive tested the Snom equipment in my office with the same panasonic pbx and it was working fine but now ive come to site and done the same installation none of the handsets are registering to the panasonic. any help would be great as im stuck what to do next. 

Regards

Wes