Tandem Telephone Exchanges helps to route traffic to other Network destinations.
Local Exchanges are connected using a defined hierarchy. A Tandem or a Transit Exchange is basically a
scaled Exchange that does not have any customer Terminations, i.e. it does not have a Main Distribution
Frame (MDF). Tandem (transit) Exchanges helps with Network redundancy / resilience. Different routes can be used based on the Network conditions.
The Signalling (e.g. SS7) is an overlay Network that operates out of band. This allows the Network to
be flexible and promotes fast Network planning. STP – Signalling Transfer Points – are used to handle signalling requests from Intelligent Network (IN) applications.