Alcatel Unleashed

When ISDN T2 lines are routed to the 4645 auto attendant,the 4646 aa menu greeting starts after the second ring (approximately 10 seconds).But when the same trunk group is routed(with same ISDN T2) to the integrated Auto Attendant, call is answered immediately.Any timer to reduce this delay in the case of 4645 VM auto attendant?
Thanks.

Trying changing the timer 251, default is 80.