You can change the waiting time by using a Telnet command to configure the delay time before the number is dialled.
Please carry out the following steps:

1. telnet into the router.
2. enter the command:

” voip dsp timer ? ”

and you will see some detail explanation come out.

3.enter the command:

” voip dsp timer 0 4 ”

and you will see

Current timer:0, PHONE_NUM_LEN=4

The first digit “0” means you will have to wait 0 sec after entering phone number.