Least Cost Routing with Phone Intelligence

What is Least-Cost Routing?

Least-cost routing (LCR) automatically selects the cheapest available route for outbound calls. Costs vary by:

• Terminating carrier — Different rates for Verizon vs. AT&T vs. T-Mobile
• Line type — Mobile termination often costs more than landline
• Geography — Some regions have higher termination costs
• Time of day — Peak vs. off-peak pricing

Why Carrier Lookup Matters

You can't do LCR based on area code alone because 30%+ of phone numbers have been ported to different carriers. For example:

• A 212 (NYC) number might have been ported to T-Mobile from AT&T
• A 415 (SF) number might now be served by a VoIP provider
• Only LRN lookup tells you the current carrier

How LCR Works

1. Carrier Identification

# Before routing, identify the terminating carrier
result = veriroute_lookup(destination_phone, lrn=True)
carrier = result['lrn']['carrier']  # "Verizon Wireless"
ocn = result['lrn']['ocn']  # "6006"

2. Rate Table Lookup

# Look up rates by carrier/OCN
rate_table = {
    "6006": {"provider_a": 0.008, "provider_b": 0.009},  # Verizon
    "6529": {"provider_a": 0.007, "provider_b": 0.008},  # T-Mobile
    "6664": {"provider_a": 0.009, "provider_b": 0.007},  # AT&T
}

3. Route Selection

# Select lowest-cost route
def get_best_route(ocn):
    rates = rate_table.get(ocn, default_rates)
    return min(rates, key=rates.get)

Implementation Patterns

Real-Time LCR

Look up carrier before each call:

• Pros: Always accurate, handles recent ports
• Cons: Adds latency, per-lookup cost
• Best for: High-value calls, low volume

Batch Pre-Lookup

Pre-populate carrier data for your contact database:

• Pros: No real-time latency, lower cost
• Cons: Data may be stale for recent ports
• Best for: High volume, campaign dialing

Hybrid Approach

def get_carrier_for_routing(phone):
    # Check cache first
    cached = get_cached_carrier(phone)
    if cached and cached.age < 30_days:
        return cached.carrier

    # Real-time lookup for uncached or stale
    result = veriroute_lookup(phone, lrn=True)
    cache_carrier(phone, result['lrn'])
    return result['lrn']['carrier']

Balancing Quality and Cost

The cheapest route isn't always the best. Consider:

Quality Factors

• Audio quality — Some routes have compression artifacts
• Latency — More hops = more delay
• Reliability — Some providers have better uptime
• Caller ID handling — Will your CNAM pass through?

Quality-Weighted LCR

# Factor in quality scores
def get_best_route(ocn):
    routes = available_routes.get(ocn, [])

    def score(route):
        cost = route.rate
        quality = route.quality_score  # 0-1
        return cost / quality  # Lower is better

    return min(routes, key=score)

Using OCN for Routing

Use OCN (Operating Company Number) instead of carrier name for reliable matching:

• Carrier names vary ("Verizon Wireless" vs "Verizon")
• OCN is always consistent (4-character code)
• Build rate tables keyed by OCN

Best Practices

1. Always use LRN lookup — Don't trust area codes
2. Cache carrier data — Reduce lookup costs
3. Use OCN for matching — More reliable than names
4. Update rate tables regularly — Carrier rates change
5. Monitor quality metrics — Don't sacrifice quality for cost
6. Have fallback routes — When preferred route fails