Question : Asterisk server - How to do paging / intercom / announcements?

I have an in-house Asterisk server and Grandstream phones.  Is there a way to setup a paging system where the secretary can make announcements over all the phones at the same time?  It only needs to be one way.

I have read some stuff about connecting a single phone to an external paging system.  This is not what I want because I don't want to buy the separate paging system.

Answer : Asterisk server - How to do paging / intercom / announcements?

The expert answer link you posted is essentially the same solution I found on wiki...

Basically you add a SIP header, to get the phones to auto answer.
You can use it with Dial cmd or Page cmd.