Before performing LCR configuration, you should consider the expansions to the network that may be required in the future.

Our example has just one system in Germany with trunk access distributed across three cities.

To facilitate additional breakouts in Germany or other countries at a later stage, the LCR should be structured from the outset so that breakouts to several countries can be configured without difficulty. One option here is the "two-level LCR" concept:

First let's consider a possible constellation of breakouts in different countries.

The following graphic shows the possible connections in such a network:

If, for example, a local station number is dialed, then the required destination depends on the source. A different destination is dialed for every location. This is why only one reroute internal is permitted within the same location for internal destinations with local station numbers. Likewise, routing should be carried out on an individual basis for each location.

If a national number is dialed, then the required destination is different in each country. Reroute internal is only permitted for national internal destinations within a country. Routing differs from country to country.

If an international number is dialed, then the destination is unique worldwide.

This is why we have divided the LCR into 2 levels.