How many calls can be made?

Given a VoIP network with these attributes:

Codec: G.728

Bit rate: 16 Kbps

WAN Bandwidth: 256 Kbps

Packet Header: 6 bytes

Payload: 40 bytes

CRTP: Yes

How many calls can be made?

A.
7 calls

B.
8 calls

C.
13 calls

D.
14 calls