Behavior of the ICS telephony module is defined by rules, which process and route income and outcome calls.
All calls are divided into dial plans (groups) of income (external) and internal and outcome rules. In the “Incoming” group are calls that are received by ICS from external tranks.
In the “Outcoming and internal calls” group are outcome calls and income calls from internal numbers. Rules are applied one by one, from top to down!
Income call from provider, the call is going to the voice menu (the rule “wait for the dial…”), during which the music is playing, and there is 15 seconds to dial the additional number.
If necessary, you can add a new dial plan and all the rules that are needed.