nonexistent or weak; the consumer might then choose to try some other location later. Whether consumers really ever or regularly monitor the field strengths of their operator while travelling around can be questioned. For most people it would be safe to assume that they do it only if they are extremely bored. Nowadays when mobile games are readily available in cellular phones monitoring the network quality in operation is quite a theoretical option. However, when people check their phones for missed calls or short messages they do subconsciously notice the field strength - at least on a level of whether there was a radio field or not. As a bottom line it can be said that the easiest and maybe the only way to improve the perception of accessibility quality is to work on improving the radio interface. Transmission Network Planning and Optimisation There is also the capacity side (or rather, say, the interference side in 3G) in the radio interface, which can be congested even if the field strength is appropriate and which is not able to be monitored by the end user. That will face similar end user perception as transmission problems of accessibility, but fixing those problems is discussed elsewhere in this book. Why is this SO important and why has all this time been spent in a transmission optimisation chapter to go through it? It is important to understand what a consumer really knows and appreciates to be able to make decisions about what is worthwhile to optimise in a transmission network. Remember that the aim is not to make a perfect system, but to maximise revenues! Accessibility problems due to poor radio interface coverage and to congested transmission result in very similar end results. The point is that the consumer has gained more understanding about accessibility problems of radio interface coverage than about problems of transmission. This is because they can monitor the radio interface with their phone (which amounts to coverage), choose where and when to make the service request and, last but not lea