[Asterisk-Users] Polycom and Presence

[Polycom User]

I am currently utilizing Polycom IP600 phones and presense.  I have
placed the hint directives in and everything seems to work fine.  But
this only works for a short period of time.  After about 30 minutes,
the extensions do not see when others are on the phone.

Has anyone seen this type of behavior before?  I am currently
utilizing v1.5.2 of the polycom software and the cvs-head release from
8/3/05.

Thanks in advance.