Before you import that CSV: 5 checks that save your next campaign

If you run campaigns from imported lists, you already know the painful pattern: the CSV looks clean in a spreadsheet, and the problems only appear after you pay to process it — or after your first sends bounce or fail.

We see the same five checks catch most of the waste before anything hits your SIP trunk, CPaaS, or CRM workflow:

1.

Format

- is the row even a phone number or email? E.164 syntax, correct country code, email syntax. Junk rows fail here first and are the cheapest to remove.

2.

Duplicates

- is the same contact in the file two or three times? If you pay per record, duplicates are pure waste. Check before verification, not after.

3.

Line type

- mobile, landline, VoIP, or premium-rate? This decides whether SMS/WhatsApp are even possible for that number.

4.

Carrier (MNP)

- which carrier serves the number

today

? Numbers port between carriers, and old carrier data misroutes you.

5.

Reachability signals

- is the number actually registered on WhatsApp / Telegram / iMessage / RCS? A perfectly valid mobile number can be completely unregistered on the channel you planned to use.

Practical habit: run a preflight on a 1-2k sample before you pay for the full file. If 15-20% fails format or duplicate checks, the rest of the file won't be better — that's useful information before you commit budget or negotiate with a list vendor.

Example: a 100k file where 12% is malformed, 8% duplicates, and 20% landline/VoIP when you only wanted mobiles — that's ~40k records you'd have paid to process or tried to message. Catching them before processing changes the economics of the whole campaign.

If you're cleaning or verifying phone/email datasets before outreach, you can check the available verification workflows at

https://phoneveriflo.com

— but the habit matters more than the tool: check before you pay to process, not after.

Curious what others do here — when a broker's list turns out to be mostly junk, do you push for a refund, re-process with different checks, or just walk away?