BUSY signal problem


this is my first topic, so do not be made if it is not in right section.
What is my problem:
In office I have two asterisk servers, one is Asterisk 11.5.1 other is Asterisk 11.17.1. They are conneted to same operator (Slovena T2) on seperate SIP Trunks. For testing I am using two phones Aastra 6757i and Aastra 6755i.
When I call from one phone (A), which is connected to first asterisk, to second phone (B), connected to second asterisk, and B phone cancel call, it send BUSY signal:
– SIP/106-00000e44 is ringing
– Got SIP response 486 “Busy Here” back from
– SIP/106-00000e44 is busy

but that BUSY signal is not send over T2 operator, because they do not sedn BUSY signal. So what I get in first Asterisk is:
SIP/RM_T2_Trunk-000001d1 is making progress passing it to SIP/704-000001d0

and after approximate 10s I get:
No one is available to answer at this time (1:0/0/0)
– Executing [s@macro-klic-ven:6] Goto(“SIP/704-000001d0”, “test-NOANSWER,1”) in new stack

I know how to change NOANSWER to BUSY signal after that, but what I wont is to decrease those 10s to 1s.
Is this “timer” adjustable somewhere in asterisk configuration or is it opreator thing?

Thank you and BR,