Last digit timeout. overlapdial=yes

Hi guys! I use AsteriskNOW with my internal PBX Lg. Lg connected to asterisk via E1. Asterisk works in overlapdial=yes mode on this connection. When somebody calls from Lg, Asterisk waits 3 seconds after the last digit and executes collected number. It’s a bit fast. How can I increase this interval to 4 or 5 sec? All calls from Lg flows in from-internal context, which generated by AsteriskNOW. I’ve heard about matchdigittimeout parameter, but I cant find it… I’ve found this http://svn.dd-wrt.com:8000/browser/src/router/asterisk/configs/mgcp.conf.sample but I don’t know what I should do with it…

Thank you!