List hygiene before you commit a route or a campaign: what a check actually catches

When a wholesale buyer evaluates a route or a bulk list, the first question is usually price per minute or per message. The second question — the one that actually determines the economics — is how much of that target base is usable.

What "checking the list" means before you commit:

**Format checks are the cheap first pass.** Imported lists contain numbers missing country codes, extra digits, spaces, hyphens. These are trivially detectable and should never reach a paid send or a routing table.

**Carrier and line-type checks change routing decisions.** A list that looks like "10,000 mobile numbers" often contains a meaningful share of landline, VoIP, toll-free, and out-of-geo entries. If your campaign or route is priced for mobile termination, those are pure waste — or worse, they fail and inflate your post-dial analysis.

**Ported numbers matter more than people expect.** Number portability means the network the number started on is often not the network that serves it today. Route on stale assumptions and you get misrouted traffic and refund disputes.

**Reachability signals beat format.** A syntactically valid number is not the same as a number that will accept delivery on the channel you are using. For messaging campaigns, checking registration or availability signals on the target platform before the send changes your delivered-per-paid-for ratio dramatically.

The operational habit worth building: **run list checks before you write the PO, not after the first failed batch.** Verification and number-intelligence APIs (phoneveriflo is one we use for exactly these checks) are cheap enough that skipping them is usually the more expensive choice.

How do others here sanity-check inbound lists from new partners before committing routes — format-only, or full carrier/line-type/reachability?