You are meeting with a customer that has deployed IP telephony at their headquarters location. They would like to roll out IP telephony to their regional office as well. They are now using the G.711 codec at headquarters. They want to be able to maximize the number of calls carried without impacting voice quality or forcing a WAN upgrade.
Which codec would be appropriate for their WAN?

A.
G.726

B.
G.723.1

C.
G.711

D.
G.729B