Voice on Frame Relay

Some customers replace private lines with FR networks to carry voice traffic between sites. Voice is compressed so that it requires less bandwidth. Customers either add separate PVCs (Permanent Virtual Circuit) for voice or upgrade their CIR (Committed Information Rate) for extra capacity. For large organizations, defining separate PVCs are cumbersome. It is also costly. Moreover, it does not guarantee quality on the access line between the customer and the frame network. These frames do not have fields capable of indicating priority levels.

Because of the quality issue, some customers do not use FR for customers' calls, only for employee-to-employee calls. If the FR network becomes congested, voice quality can be degraded because packets are dropped or delayed even with higher CIRs.

The desire to add voice between sites is another factor in customers' migration to MPLS (Multiprotocol Label Switching) because of this extra expense to upgrade FR service and the lack of prioritization on the access line. This is particularly true for larger organizations that want to send customer traffic between sites.