https://www.cisco.com/c/en/us/td/docs/ios/dial/configuration/guide/15_0s/dia_15_0s_book/dia_v92_hold_acc_svr.html
Dial Configuration Guide, Cisco IOS Release 15.0S - V.92 Modem on Hold for Cisco AS5300 and Cisco...
V.92 Modem on Hold for Cisco AS5300 and Cisco AS5800 Universal Access Servers