By default Digium phones and newer FreePBX versions mated together will ring and then intercom for intercom and paging calls (alert info ring-answer which is the default). You can force the Digiums to auto answer a page or intercom call without the leading ring using the following cli commands to modify the paging piece of the database.

fwconsole mysql m
update paging_autoanswer set setting='intercom' where useragent='Digium'
quit
fwconsole reload