Your PSTN carrier sends digits to your T1 PRI circuit in a digit-by-digit format. How must the T1 PRI circuit be configured to support this capability?

A.
The T1 PRI controller supports either en-bloc or digit-by-digit formats natively.

B.
The serial interface that is associated with the T1 controller needs to include the isdn incoming- voice command.

C.
The T1 controller needs to include the isdn overlap-receiving command.

D.
The serial interface that is associated with the T1/E1 controller needs to include the isdn overlap-receiving command.

Explanation:

Configuring Overlap-receiving on the D-channel changes the way routers behave when receiving ISDN calls. Overlap receiving allows the matching of dial peers as the digits are being received. The router responds to the setup message with a SETUP ACK. This informs the network that it is ready to receive further information messages containing additional call routing elements.

http://www.cisco.com/en/US/tech/tk801/tk133/technologies_tech_note09186a00800b48cb.shtml