The most common use of the policy-based routing is to create separate routing for voice and data traffic.

The following figure uses the DSCP field to identify VoIP control packets (DSCP = 34, 41), VoIP Bearer RESV packets (DSCP = 43, 44), and VoIP Bearer packets (DSCP = 46). Policy-based routing sends these packets over the T1 WAN line, and sends other packets over the Internet. This saves bandwidth on the more expensive external Serial interface.