Insights from the ZelNum team

Phone Validation 5 min read

HLR Lookup for Mobile Network Operators

HLR Lookup for Mobile Network Operators A number range table goes stale the moment a subscriber ports out. That's the core problem HLR lookup exists to...

Phone Validation 4 min read

Phone Line Type Checker: Mobile vs Landline vs VoIP

Phone Line Type Checker: Mobile vs Landline vs VoIP Knowing whether a phone number is mobile, landline, or VoIP changes what you do with it. Mobiles...

Phone Validation 4 min read

Carrier Lookup API Workflow for Automated Checks

<h2Carrier Lookup API Workflow for Automated Checks</h2 <pBuilding carrier lookup into your pipeline means more than hitting an endpoint. You need...

Phone Validation 5 min read

Phone Line Type Checker API Workflow for Automated Checks

<h2Phone Line Type Checker API Workflow for Automated Checks</h2 <pThis isn&8217;t a theory page — it&8217;s about building an automated pipeline for...

Phone Validation 4 min read

Carrier Lookup Use Cases for List Hygiene and Risk Review

<h2Carrier Lookup Use Cases for List Hygiene and Risk Review</h2 <pThis isn&8217;t a theory page — it&8217;s about deciding what to do with a list of...

Phone Validation 5 min read

VoIP Numbers: What They Are & How to Detect Them

<h2VoIP Numbers: What They Are & How to Detect Them</h2 <pA VoIP (Voice over IP) number is a phone number that routes calls over the internet...

Phone Validation 5 min read

How to Validate Phone Numbers: Step-by-Step Guide

<h2How to Validate Phone Numbers: Step-by-Step Guide</h2 <pIf your phone list has grown past what you can check by hand, you need a bulk validator. <a...

Phone Validation 3 min read

How to Use Signal Number Checker for Bulk List Checks

Signal is a privacy-first messenger, and the check there answers one question: is this number tied to a Signal account? That matters for teams routing...

Phone Validation 3 min read

Social Media Account Lookup for Investigators

Investigators work with fragments: a phone number here, an email there, a username in a report. The question is usually the same: is there an account...

Phone Validation 6 min read

Telemarketing List Scrubbing: DNC, Dead Numbers & Compliance

<h2Telemarketing List Scrubbing: DNC, Dead Numbers & Compliance</h2 <h2TL;DR</h2 <ul <liTelemarketing list scrubbing covers two separate problems:...

Phone Validation 6 min read

What Is Data Scrubbing? Data Scrubbing vs Cleansing Explained

<h2What Is Data Scrubbing? Data Scrubbing vs Data Cleansing Explained</h2 <h2TL;DR</h2 <ul <liData scrubbing is the process of removing outdated,...

Phone Validation 6 min read

How to Reduce SMS Bounce Rate: 6 Fixes That Work

<h2How to Reduce SMS Bounce Rate: 6 Fixes That Work</h2 <h2TL;DR</h2 <ul <liA bounce happens when an SMS fails to reach a phone; a hard bounce is...