How can this be accomplished?

When an external call is placed from Ajax, they would like the ANI that is sent to the PSTN to be the main number, not the extension. For domestic calls, they would
like 10 digits sent; for international calls, they would like to send the country code 1 and the 10 digits. How can this be accomplished?

A.
Add a translation pattern to the dial peers in the gateway that adds the appropriate digits to the outgoing ANI.

B.
In the external call route patterns, set the external phone number mask to the main number. Use 10 digits in the domestic route pattern and 1 followed by the
main number digits in the international route patterns.

C.
Use a calling party transform mask for each route group in the corresponding route list configuration. Set the explicit 10-digit main number for domestic calls and
1 followed by the main number for the international route patterns.

D.
In the directory number configurations, set the prefix digits field to the country code and the 10 digits of the main number. This will be truncated to the 10-digit
number for domestic calls and sent out in its entirety for international calls.

Explanation:
Incorrect answer: A, B, D

calling party transformation mask value is Valid entries for the NANP include the digits 0 through 9; the wildcard characters X, asterisk (*), and
octothorpe (#); and the international escape character +.
Link: http://www.cisco.com/en/US/docs/voice_ip_comm/cucmbe/admin/8_6_1/ccmcfg/b03trpat.html