Ok…I think you are confusing this a bit…
On which Page Group? Both of them or just the Emergency 7001?
- If only Emergency 7001 HAS Whisper and Normal 7002 does NOT, Normal 7002 will NOT be able to interrupt Emergency.
- If BOTH have Whisper set, either 7001 OR 7002 will be able to interrupt (play over) the other…BUT, while NOT having Whisper enabled on Normal 7002 would prevent it from interrupting Emergency pages, it will ALSO prevent it from speaking the Normal page to those who are on a call even when there is not an Emergency, which may or may not be desired behavior.
Using FORCE will have varying effects depending on the Devices involved, with most of them merely treating the Page call like any other “call waiting” type of call if they are already busy…there will be no announcement played for them unless they actually ANSWER that Page call, which would place their original call on hold or hang up on them. It is nonsensical in that way, as most modern devices won’t actually force the announcement to be heard without requiring user intervention to switch calls.
You should definitely use WHISPER as your Busy option. I don’t know of any modern devices that behave with FORCE like you’d expect them to, making the option useless. Whisper is very much “device agnostic,” as Asterisk is merely mixing in the Page audio with the existing call directly at the PBX, requiring no action or explicit support from SIP/PJSIP devices.
Since WHISPER and FORCE only apply to devices on a call at the time, neither option will affect how idle phones behave when a Page call comes in. Most devices support the intercom auto-answer by default, but some will require an extra option to be enabled in their config if their intercom auto-answer is disabled by default.