Implementing Carrier Cost Arbitrage Systems for Least-Cost Routing of Outbound Calls

How-To-Articles
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Implementing Carrier Cost Arbitrage Systems for Least-Cost Routing of Outbound Calls

What This Guide Covers

  • Architecting a “Least-Cost Routing” (LCR) engine for high-volume outbound contact centers.
  • Implementing real-time SIP trunk failover and cost-based route selection using Genesys Cloud BYOC.
  • Designing a financial model that exploits “Rate Deck” differences between telecom carriers (Carrier Arbitrage).

Prerequisites, Roles & Licensing

  • Licensing: Genesys Cloud CX 1/2/3 with BYOC (Bring Your Own Carrier) Premises or Cloud.
  • Tools: Multiple SIP Trunk Providers (e.g., Twilio, Bandwidth, local telcos), Rate Deck Analyzer.
  • Stakeholders: Voice Engineers, Telecom Managers, and FinOps.

The Implementation Deep-Dive

1. The Strategy: The Telecom Arbitrage Opportunity

If you run a high-volume outbound dialer (e.g., Collections, Sales), telecom costs are your primary margin killer. “Rate Decks” are massive spreadsheets from carriers listing the per-minute cost to call every area code in the world. Carrier A might charge $0.01/min to call London, while Carrier B charges $0.005/min. Least-Cost Routing (LCR) is the automated process of sending each call out the SIP trunk that offers the cheapest rate for that specific number.

The Strategy:

  1. The Infrastructure: Establish active SIP trunks with at least 3 different telecom carriers.
  2. The Intelligence: Maintain a routing table that maps Dial_Prefix to Cheapest_Carrier.
  3. The Execution: Configure Genesys Cloud Outbound Routes to process the LCR table.

2. Implementing the LCR Routing Engine in BYOC

You need to instruct Genesys Cloud how to choose the right trunk.

The Implementation:

  1. The Setup: In Genesys Cloud, navigate to Telephony → Trunks. Configure Trunk A, Trunk B, and Trunk C.
  2. The Number Plans: Create specific Number Plans for high-cost or high-volume regions.
    • Example: Match +44 7* (UK Mobile numbers).
  3. The Outbound Routes: Create a new Outbound Route linked to the Number Plan.
  4. The Routing Order (The Arbitrage): Under the Outbound Route, assign the Trunks in order of Cost.
    • Priority 1: Trunk B (Cheapest - $0.005/min)
    • Priority 2: Trunk C (Backup - $0.007/min)
    • Priority 3: Trunk A (Premium/Failover - $0.012/min)

3. Designing the “Rate Deck” Ingestion Pipeline

Telecom rates change constantly. A static routing table will become expensive very quickly.

The Strategy:

  1. The Download: Write a script that automatically downloads the latest Rate Deck CSVs from your carriers via API or SFTP on the 1st of every month.
  2. The Calculation: Load the CSVs into a database (e.g., PostgreSQL). Run a query:
    SELECT prefix, MIN(cost) as cheapest_cost, carrier
FROM rate_decks
GROUP BY prefix;
  3. The Update: The script must highlight “Routing Changes” (e.g., Carrier A is no longer the cheapest for prefix +44). The Voice Engineer then updates the Genesys Cloud Outbound Routes accordingly.

4. Implementing “Quality-Aware” LCR (The Safety Net)

“Cheap” often means “Low Quality.” If a cheap carrier drops 10% of your outbound sales calls, the lost revenue far exceeds the telecom savings.

The Implementation:

  1. The Monitor: Continuously monitor the ASR (Answer Seizure Ratio) and ALOC (Average Length of Call) for each SIP Trunk.
  2. The Logic: If the ASR on the “Cheapest Trunk” drops below $60%$ (indicating the carrier is failing to connect calls), or if the MOS (Mean Opinion Score) drops below 3.5 (poor audio).
  3. The Action: The Voice Engineer must manually (or via API) disable that trunk in the Genesys Cloud Outbound Route, forcing traffic to the “Priority 2” trunk until the cheap carrier resolves their network issue.

Validation, Edge Cases & Troubleshooting

Edge Case 1: The “Minimum Commitment” Trap

Failure Condition: You route 99% of your traffic to Carrier B because they are the cheapest. At the end of the month, Carrier A hits you with a $5,000 “Minimum Usage Penalty” because you didn’t send them enough traffic, wiping out all your arbitrage savings.
Solution: Implement Commitment-Aware Routing. Your LCR algorithm must factor in contract minimums. You may need to artificially route some traffic over a slightly more expensive trunk specifically to satisfy a contractual minimum and avoid a larger penalty.

Edge Case 2: Post-Dial Delay (PDD) Spikes

Failure Condition: “Discount” carriers often achieve low rates by routing calls through 5 different sub-carriers before reaching the destination. This causes a 6-second “Dead Air” silence before the phone rings (PDD). Customers hang up before the call connects.
Solution: Monitor PDD Metrics in your SIP traces. If a discount route has a PDD $> 3$ seconds, it should be disqualified from the LCR table for any customer-facing outbound dialing.

Edge Case 3: “CLI Clipping” (Caller ID Issues)

Failure Condition: You use LCR for an outbound campaign, but the cheap international carrier fails to pass your correct Caller ID (CLI) to the destination network. The customer sees “Unknown Number” and ignores the call, plummeting your connection rate.
Solution: Conduct Test Calls. Before committing major traffic to a new discount route, use a service like “Spearline” to place automated test calls over that specific trunk to verify that your Caller ID is accurately transmitted to the end user.

Official References