ts to the PIC. In a switched-to-switched connection, it does not matter what PIC the called party uses. Circuit-switched Networks In a switched-to-dedicated access connection, an extra step may be required, but only if the called party uses a different IXC than the caller. When a difference exists, the caller dials a five-digit carrier access code, which forces the call over the long distance network that serves the called party. Examples of carrier access codes include 10288 for AT&T, 10222 for MCI, and 10333 for Sprint. Switched access is easy to use but it has two cost-related drawbacks. First, IXCs typically offer lower rates for calls conducted over dedicated access arrangements than for switched access calls. The reason for this is simple. An IXC must pay the LEC a per-minute fee for long distance calls that pass over the local network. This fee does not apply when a call originates over a dedicated access connection-in that case, the LEC gets its compensation in the form of a private line monthly rental charge. IXCs pass the additional cost of switched access on to their customers. Consequently, the cost for switched-to-switched connections is higher than dedicated-to-dedicated connections. The second reason that switched access might be more costly is duplication. Most companies that are in the position to install video communication have at least one, if not more, T-1 connections to an IXC. Often there are channels standing idle. It seems logical to use these channels for video communication, and thereby eliminate a separate monthly cost for switched access. However, an IXC often charges a sub- multiplexing fee to split out video communication channels from the rest of a T-1 pipe. That charge can, in some cases, equal or exceed the cost of separate switched digital access channels. Several categories of switched digital access service exist. Before we continue, we should further examine network signaling and control methods. Differences between signaling systems may affect the type of switched digital se