Time interval within trunk sequence

In each of outbond routings, I defined a trunk sequence with 2 trunks (trunk1 and trunk2).

If trunk1 is not available (because voip provider is down, for instance), system waits by default 60 s before try trunk2.

How can i reduce that time interval?

With voip providers that do not accept “qualify=yes” like Sipdiscount, Voipbuster and Voipstunt, when qualify is set to yes in trunks configuration, status in info panel changes from “unmonitored” to “unreachable”.

So, when a call is made the message “all circuits are busy now” sounds.

It must exist a way to short the time needed to go to the next trunk in the sequence, when voip providers that do not accept qualify command are used.