Significance of Least Cost Routing (LCR) Systems
Least Cost Routing (LCR) simply refers to the process of determining the least expensive way to make a phone call, as the name suggests. The process involves monitoring, choosing, and controlling the
path of inbound and outbound communications traffic, based on the path that offers optimal call quality and rates. For instance, if a telecommunications company in New Delhi wants to choose a call path to
New York, they will obtain the calling rates of a selection of New York-based telecommunications companies, and then select the one that offers the best quality at the best rate.
In least cost routing, organizations that intercommunicate with other networks take advantage of the opportunity to reduce their telecommunications expenses by choosing to route their calls through telecom
networks that complete calls at the best rate. A software company implements an LCR system for its clients' telephone calls by making a routing table that corresponds with telephone dial codes, together
with a list of network destinations ranked by cost. Skilled technicians can create routing tables. However, customized least cost routing software is used for the process to quickly create optimized routing
tables that may consist of tens of millions of routes. A good example of this software is LCR as a Service.
Formerly, the prevailing practice was directly exporting the routing table to a Private Branch Exchange or a telephone switch. This method, however, has two main pitfalls. For one, telecom signaling
platforms, such as next generation soft switches or the previously used Public Switched Telephone Network (PSTN) switches lack adequate memory and can, thus, not handle routing tables from a few
million call routes. Complete profit optimization is not possible when tables this size are routed. The process is painstakingly long under conditions of heavy traffic load, and this time is not acceptable to
operators that with to quickly update routes.
Nowadays, Next Generation Networks make use of an alternative algorithm to offer ever-evolving least cost routing comprising tens of millions of routes. In order for real-time LCR instructions to be provided
to more than one switch on a call by call basis, this modern technique makes use of an external routing engine. Therefore, the routing software will export optimized routing tables to the external engine
instead of pushing the tables directly to the switch. The typically Linux-based Next Generation Networks routing engines have enough memory to host routes in the tens of millions, in addition to holding a
number portability database with numbers in the hundreds of millions.
The NGN switch, upon receiving a call, retrieves instructions from the external engine, a process that takes a fraction of a second, excluding network delays. The communication protocol between an NGN
external routing server and a telecom switch is the E.164 Number Mapping (ENUM), Open Settlement Protocol (OSP), or the Session Initiation Protocol (SIP). OSP and SIP are the most popular because they
have the capability to support a number of advanced routing features, such as class of service routing, trunk group routing and jurisdictional routing.