My answer to the question: How Accurate are Zoominfo Direct Dials?
There are two sets of contact information from Zoominfo: Tier 1 validated contacts for around 5 million global executives and decisionmakers. This data is re-validated every 90 days and has a 96% direct dial population rate and 98% email. These records are subject to a 95% data accuracy SLA (100% is impossible as there is a 2 – 2 1/2% decay rate of contact records per month). Tier 1 data also includes org charts, researched biographies, and company projects.
Tier 2 data is obtained through machine learning and natural language processing. Zoominfo obtains this data through web crawling and the mining of signature blocks amongst its Community Members (small businesses that provide access to this data in exchange for limited platform access). Because this data is being gathered constantly, Zoominfo has a heads up if somebody’s signature block changes. It also provides a deeper set of direct dials than available from other companies. Zoominfo offers an update date for Tier 2 data which I would recommend using. Data verified within the past six months should be around 90% accurate. At a year, the accuracy is likely around 75% and could be lower. Anything beyond a year is likely to be of low quality and should not be purchased except in special circumstances such as the lack of new contacts at a key function of an account or high-value prospect.
I have not conducted a recent study of Tier 2 data vs. other contact data sources, so cannot speak to its quality.
Two other vendors directly collect and verify contact direct phones and emails. If direct-dial accuracy is a key concern, also evaluate DealSignal and SalesIntel.io. DealSignal performs overnight reverification so