asterisk users - Apr 2005 - Stable Asterisk Version ??? / SIP problem ???

I'm currently using *-1.0.5 with SPA-3000

When I or somebody dial from outside one of my extension "218"
asterisk
execute for example '22' (entry below):

-- Invalid extension '22' in context 'office-open' on
SIP/pstn-spa3k-2f96

Sometimes when I dial 218 it goes through just fine but sometime it
dials wrong entry.
What could be causing this problem?

If I can not solve the problem I'll have to go down to ver.0.9 (the
latest stable version marked in Gentoo portage).
In ver. 1.0.6 and 1.0.7 SIP wasn't working correctly.

-- 
#Joseph