About Nummernindex

Understanding phone numbers: area codes and number ranges, spotting spam and one-ring calls, premium-rate costs, blocking numbers and reporting abuse.

Who runs this site

Nummernindex is written and maintained by the editorial team at OnlineBuilders LLC, a U.S. technology studio founded in 2020 in Delaware that builds and runs its own SaaS, AI and data platforms. What you read here comes out of that work: projects, tenders, mistakes, and the questions clients and founders ask us.

How we work

• Figures, deadlines and legal rules are backed by primary sources: statutes, public authorities, statistics offices, official documentation.
• Where no reliable figure exists, we give a range or mark the value as an estimate from experience.
• Every article shows the date it was last reviewed. When a rule changes, the article is revised, not just re-dated.
• We do not sell placements or take commissions on recommendations. Links to OnlineBuilders are clearly marked.

Found a mistake?

Write to [email protected]. We publish corrections with a date.