Quick sanity checks on number lists before you commit a route or a campaign

We see a lot of the same list problems on both the carrier and the campaign side, so sharing the checks that save the most money - happy to hear what others do too.

1. Normalize first. Mixed formats (missing country code, dashes, spaces, local formats) silently kill a percentage of any route or send. E.164 normalization catches most of it before anything else.

2. Deduplicate. The same number appearing twice or three times in one list means double billing on termination or sends - and it happens more than people expect.

3. Know the line type. Mobile vs VoIP vs landline changes route selection and cost. A list heavy on VoIP/landline numbers behaves very differently from a mobile list, and if you are checking messaging eligibility (WhatsApp/Telegram/RCS), non-mobile numbers will mostly never register.

4. Check assignment/porting status before big batches. Carrier lookup tells you whether a number is still assigned and which network it sits on now (numbers port between operators all the time).

We built PhoneVeriflo (phoneveriflo.com) to automate exactly these checks - phone/email validation, carrier and line-type intelligence, WhatsApp/Telegram/iMessage registration signals, bulk files + API, with a free preflight before any paid job. Not here to pitch anyone, but if you handle large lists it is a genuinely useful data point.

What is the biggest number-quality problem you see in your own lists?