Click the matching criteria for inbound POTS calls on the left and drag them to the order of selection on the right.

Explanation/Reference:
Explanation:
The router or gateway matches these items in this order:
1. Called number (DNIS) with the incoming called-number command. First, the router or gateway attempts to match the called number of the call setup request with the configured incoming called-number of each dial peer. Because call setups always include DNIS information, it is recommended to use the incoming callednumber command for inbound dial peer matching
2. Calling Number (ANI) with the answer-address command If no match is found in step 1, the router or gateway attempts to match the calling number of the call setup request with the answer-address of each dial peer. This attribute can be useful in situations where you want to match calls based on the calling number (originating)
3. Calling Number (ANI) with the destination-pattern command If no match is found in step 2, the router or gateway attempts to match the calling number of the call setup request to the destination-pattern of each dial peer. For more information about this, see the first bullet in the destination-pattern of each dial peer. For more information about this, see the first bullet in the Dial Peer Additional Information section of this document.
4. Originating Voice-port (associated with the incoming call setup request) with configured dial peer port ( applicable for inbound POTS call legs) If no match is found in the step 3, the router or gateway attempts to match the configured dial peer port to the voice-port associated with the incoming call. If multiple dial peers have the same port configured, the dial peer first added in the configuration is matched.
5. If no match is found in the first four steps, then the default dial peer 0 (pid:0)command is used.
LINK: http://www.cisco.com/en/US/tech/tk652/tk90/technologies_tech_note09186a008010fed1.shtml