There is no fixed configuration that indicates which channels are used for outbound or inbound calls. They are used for any type of call if they are free.
The Cisco CallManager uses an order defined to look for available channels when outbound calls are placed.
The Telco uses their own order to look for available channels when inbound calls are sent to the site.
Usually the order configured in Cisco CallManager for outbound calls is the opposite of the Telco for inbound calls in order to increase the likelihood ofavailable channels. Then, the call is placed.
Refer to Gateway Configuration for more information.