The default behavior is for the ad-hoc conference to continue until two participants remain, at which point the call drops back to a direct call. That distinction is important if you want to prevent this.
There are two CUCM Service Parameters under the Cisco CallManager service:
- Drop Ad Hoc Conference: This parameter determines how an Ad Hoc conference terminates. Valid values follow:
Never - The conference remains active a) after the conference controller hangs, and b) after all OnNet parties hang up. Be aware that choosing this option means that if OnNet parties conference in OffNet parties and then disconnect, the conference stays active between the OffNet parties, which could result in potential toll fraud.
When Conference Controller Leaves - Terminate the conference when the conference controller hangs up or when the conference controller transfers, redirects, or parks the conference call and the retrieving party hangs up.
When No OnNet Parties Remain in the Conference - Terminate the conference when there are no OnNet parties remaining in the conference.
This is a required field.
Default: Never
- Block OffNet To OffNet Transfer: This parameter determines whether transfers between external (OffNet) parties are blocked (not allowed). Valid values specify True (block transfers between OffNet parties) or False (allow transfers between OffNet parties).
This is a required field.
Default: False
For your example where there are five people in an ad-hoc conference and the initiator leaves, changing Drop Ad Hoc Conference to a setting other than Never will cause the conference to end and hang up on the remaining participants. Be careful that this applies to all conferences system-wide, even simple three-way calls.
You may also need to set the Block OffNet To OffNet Transfer to True and ensure that all Gateways or Trunks that face the PSTN are classified as an OffNet destination. The may be necessary (i.e. you should test this) on a three-way call where the initiator drops. At that point the call effectively becomes a transfer and not a conference. I'm just not certain whether Drop Ad Hoc Conference would cover this scenario or not. Use caution though as this would prevent anyone from transferring a offnet call back out to the PSTN (e.g. someone calls the receptionist and she wants to transfer to an employee's cell phone).
