Wholesale VoIP for carriers who judge by ASR, not adjectives

A wholesale VoIP provider sells bulk call termination, origination, and numbering capacity to other carriers, ITSPs, and call centers — priced per-minute or per-destination — rather than selling finished phone service directly to end users. Retail providers are often themselves a wholesale provider's customer.

A-Z termination means a provider can complete (terminate) calls to virtually any destination worldwide, from country "A" to country "Z." Buyers typically receive a rate deck priced by destination/prefix and are billed on actual usage.

LCR is the practice of automatically routing each call over the lowest-cost available path. Naive LCR chases price alone; a properly built LCR engine also weighs ASR, ACD, and post-dial delay, because the cheapest route to a destination is worthless if it produces poor answer rates or dropped calls.

ASR (Answer Seizure Ratio) measures the percentage of call attempts that get answered; ACD (Average Call Duration) measures how long answered calls last. Together they're the clearest signal of real route quality — a provider unwilling to share these metrics per-route is harder to hold accountable than one that will.

International Revenue Share Fraud (IRSF) happens when a compromised PBX, trunk, or voicemail system is used to pump calls to premium-rate or fraud-controlled international numbers, generating termination charges that benefit the fraudster. It's controlled through velocity monitoring, destination risk-scoring, real-time spend caps, and encrypted signaling — not eliminated outright, but caught early rather than discovered on an invoice.

For US-bound wholesale traffic, FCC caller ID authentication rules (STIR/SHAKEN, under 47 CFR Part 64 Subpart HH) govern how calls are digitally signed and attested as they pass between carriers. Traffic with poor or missing attestation is more likely to be flagged, down-ranked, or blocked by terminating carriers, which is why CLI handling matters when selecting an upstream wholesale partner.

At minimum: the provider's underlying carrier interconnects (direct vs. resold), regulatory standing in the jurisdictions being terminated into, CLI/caller ID authentication handling for US traffic, and contract terms around fraud liability and billing disputes.

Most wholesale voice is billed per-minute (sometimes per-second after initial billing increments) by destination and route quality tier, with volume-based rate tiers common for high-usage buyers. Rates fluctuate with destination, time of day in some markets, and route quality guarantees.

A direct carrier terminates traffic on its own interconnects and infrastructure; a reseller buys capacity from an upstream carrier and marks it up, adding a layer between the buyer and the actual terminating network — which can mean less visibility and slower resolution when quality issues occur.

Request per-route ASR/ACD data, ask specifically how IRSF and toll fraud are monitored (not just "we have fraud protection"), confirm CLI/STIR-SHAKEN handling for US traffic, and start with a smaller test allocation across your actual destination mix before moving full volume.