Sounds like they are completeing a transfer instead of a conference. If there is an IP phone involved in the call, does their phone display To Conference or To ?
Conference Steps: During an active call, user presses hookflash for dial tone, dials a third party, and then presses hookflash again to connect all three parties.
Transfer Steps: During an active call, user presses hookflash and receives dial tone. User dials number for transfer and either stays online to announce (consultive transfer) or hangs up (blind transfer). When user hangs up, the call is transferred
From: http://www.cisco.com/en/US/docs/ios/voice/fxs/configuration/guide/fxssccpsplmft.html
Is this isolated to a specific analog phone model? Perhaps the VG224 is interupting the second hookflash as a hangup event and the timer needs to be adjusted.
The FXS voice port (RemoteSite router) uses the timing hookflash-in msec command where msec is the maximum value of a loop break (in milliseconds) from the telephone handset that is interpreted as a hookflash. A loop break greater than the configured value is regarded as a disconnect and the call is dropped. Any interval under this value causes the router to send the '!' character via the H.245-signal DTMF relay.
The FXO voice port (MainSite router) uses the timing hookflash-out msec command where msec is the duration of the outgoing loop break in milliseconds. When the router receives an H.245-signal DTMF relay signal, the FXO port generates a loop break for the configured interval.
From: http://www.cisco.com/en/US/tech/tk1077/technologies_configuration_example09186a008009431b.shtml
