to waste. The downside to packet, cell and frame networks is that they were designed to carry data traffic primarily and only recently have been able to approach the quality and reliability TDM networks provide for voice services. Latency, or the inability for traffic to get from one end of a call to the other in time, is still a major issue. The fluctuations in quality and differences in traffic handling have had a significant impact on billing. 5.4 Billing Schemes For data services, tiered billing is common. A tiered billing scheme prices service according to usage thresholds. The customer will pay, for example, according to the range within which its average monthly bandwidth usage falls. For example, a customer may have the ability to use up to 1.5 Mbps - an amount it hits once a month during a monthly, batch data transfer. The rest of the month, usage is less, making the customer's average usage only 522 kbps. The customer probably pays a premium for the right to "burst" up to 1.5 mbps, but it only pays the fee associated with the 450-600 kbps tier for its average usage. As voice and data networks converge, several factors become more relevant for billing - guaranteed QoS, traffic type, and total bandwidth used. Quality of service is perhaps the most critical factor. Different QoS levels are assigned to give certain traffic streams priority over others. Customers will pay a premium for guaranteed traffic delivery, up to a certain capacity. For example, a frame relay customer might be permitted to burst to 1.5 mbps, but only pays to guarantee traffic up to 756 kbps. The network operator sets its frame relay connection with a 756 Kbps committed information rate (CIR). The network will thus mark any frames above that CIR "discard eligible." Chances are the traffic will get through, but if it hits a congestion point in the network, those marked frames will be dropped. Some IICs have pricing plans The Ultimate Guide to Building and Delivering OSS/BSS that allow for some level of "bursting" above the CIR, for whic