Guides
How to get a phone list into a state where your campaign does not waste money on numbers that were never going to answer.
What E.164 is, and why your list probably isn't in it
E.164 is the international format every SMS gateway and dialler expects. Here is the rule, the four mistakes that break it, and how to convert a messy export without guessing.
How to clean a phone list before an SMS campaign
A sequenced checklist for scrubbing a phone list before you send: deduplicate, normalise, drop unallocated numbers, remove landlines, then enrich only what is left.
Mobile, landline or VoIP: why line type decides your bounce rate
What line type actually means, how it is determined from a numbering plan, why ported numbers are the known limitation, and how to act on each type.
How to clean a phone list before importing it to Klaviyo
Klaviyo rejects phone numbers that are not in E.164 and charges you for SMS to landlines. Here is how to prepare the file so the import runs clean the first time.
What phone validation actually costs
Published per-lookup API rates, worked examples on a 100,000-row list, and where a local numbering-plan pass changes the arithmetic.