Refer to the Bellcore Style section of How To use Pre-call and Mid-Call Services.
To configure the Bellcore style call conference, perform these steps:
Issue the dual line ephone-dn command for Analog Telephone Adaptor (ATA).
From the debug, when you perform the first hookflash to hold the current call, the system thinks it is the transfer event, as shown:
ephone-3[ATA00070EDCCD03]:SoftKeyEventMessage event 4 line 1 callref 15 (event 4 means transfer)
When you perform the second hookflash, the system knows it is for a conference event, and the Cisco CallManager Express connects the conference bridge, as shown:
ephone-3[ATA00070EDCCD03]:SoftKeyEventMessage event 13 line 1 callref 17 (event 13 means conference)
ATA 180 Series Analog Telephone Adaptor