LCR (Least Cost Routing) is a process used by telecommunications carriers and enterprises to route outbound calls through the least expensive available route while maintaining acceptable call quality. LCR systems compare real-time rates from multiple termination carriers and select the optimal route based on cost, quality metrics (ASR, ACD), and regulatory compliance. Enterprise telephony systems and carrier switches implement LCR to reduce per-minute termination costs on high-volume outbound traffic.
LCR (Least Cost Routing) is the automated selection of the lowest-cost available carrier route for each outbound call, applied in real time as calls are placed. A telecoms switch or softswitch checks rates from multiple carrier interconnections for the destination being called, then selects the cheapest route that meets defined quality thresholds. For carriers and large enterprises routing millions of call minutes per month, LCR can deliver significant cost savings by continuously optimising the carrier mix without manual route management.
LCR works by maintaining a real-time database of carrier rates and quality metrics for each international prefix. When a call is placed, the LCR engine looks up the destination prefix, retrieves current rates from all available carrier interconnections, ranks them by cost (subject to quality filters), and routes the call to the cheapest qualifying carrier. Most LCR systems apply quality gates — minimum ASR, ACD thresholds — to prevent routing to cheap carriers with poor completion rates. Routes are dynamically updated as carrier rate decks change.
LCR (Least Cost Routing) optimises primarily for cost, selecting the cheapest route that meets a minimum quality bar. Quality-based routing — sometimes called QBR or Premium Routing — optimises for call quality metrics (ASR, ACD, post-dial delay) first, with cost as a secondary consideration. Many carriers and enterprises use a hybrid approach: route standard traffic via LCR to manage costs, and route high-value traffic (VIP customer calls, regulated services, contact centre agents) via quality-optimised Platinum routes where answer rates and call clarity are commercially critical.
Poorly configured LCR can degrade call quality by routing calls through the cheapest possible carriers regardless of network congestion, routing depth (number of intermediary carriers), or CLI integrity. Low-cost routes often involve multiple carrier hops, increasing latency and the risk of echo, distortion, or dropped calls. Well-configured LCR balances cost and quality by setting minimum ASR and ACD thresholds as filters before cost ranking. IDT Express Platinum routes are designed for businesses that need reliable quality: they use direct carrier interconnections with quality guarantees, not pure cost optimisation.
