An account manager is meeting with a customer running Cisco 2800 Series Integrated Services Routers with a Cisco Unity Express Advanced Integration Module at various branch offices. Currently, there are enough mailboxes, and the limit of allowed mailboxes has not been reached. However, the customer is concerned about running out of voice mailboxes because of an expected 25 percent growth across branches.

What should you recommend to the customer?

A.
Upgrade the Cisco IOS software.

B.
Upgrade to Cisco 3800 Series Integrated Services Routers.

C.
Swap Cisco Unity Express Advanced Integration Module with a Cisco Unity Express Network Module.

D.
Migrate to Cisco Unity.