B2B contact-database purchases have a particular failure mode. The vendor delivers a sample file that looks excellent. Procurement signs a twelve-month contract based on that sample. Six months in, the marketing team reports that deliverability has collapsed, phone numbers are dead, and the 'verified' titles no longer match LinkedIn. The sample was a curated subset. The production feed was not. The contract has nine months left. This pattern is common enough that most experienced B2B marketing operators now run a five-question diligence process before signing anything, regardless of the vendor's reputation. GSDSI maintains a 486M+ global B2B contact database and has answered every one of these questions for sophisticated buyers — here is the diligence framework.
Every vendor quotes a headline count — 200 million contacts, 480 million contacts, some larger number. The number is almost never the right number to evaluate. What matters is coverage against the specific segments the buyer cares about. A team targeting CFOs at venture-backed SaaS companies between 100 and 1,000 employees in North America has a total addressable universe of roughly 40,000 people. A database with 400 million global contacts might have only 25,000 of those 40,000; a smaller, more focused database might have 38,000 of them. The right evaluation ask is not 'how many contacts do you have' but 'how many contacts do you have that match this exact ICP, and can you prove it with a hashed match against our customer list so we can verify without you seeing our data?' Vendors that can run that match in a clean room are the ones worth continuing with. This is standard practice in B2B prospecting programs run by teams that have evaluated more than one vendor.
Professional contact data decays quickly — somewhere between 2% and 4% per month depending on the industry and seniority level, which means a database that was 90% accurate on signing day is 70–75% accurate a year later if nothing is being refreshed. The vendor's answer to 'how often do you re-verify email deliverability' and 'what is your source for title changes' tells the buyer how fast the file will rot. The best providers combine email-bounce re-validation with a set of third-party signals — job-change APIs, payroll-processor cooperative data, social-profile scraping — and they can cite the specific cadence per field. Vendors who cannot answer this question precisely are outsourcing the decay problem to the buyer's marketing team. For teams also running dedicated email data append and enrichment programs, confirm the refresh cadence aligns across vendors so the enrichment layer isn't older than the base file.
Many B2B vendors bundle 'mobile direct dials' into their pitch as though the number itself is the deliverable. Under the Telephone Consumer Protection Act and current FTC Telemarketing Sales Rule enforcement, calling a mobile number without proper consent can cost the buyer $500 to $1,500 per call in statutory damages, and the plaintiffs' bar treats B2B mobile calling as a live hunting ground. The buyer should ask: where did you source these mobile numbers? Do you have a documented consent artifact for each? If the consumer disputes the call, what evidence can you produce? Vendors who cannot provide consent documentation inline with the records are creating compliance exposure the buyer inherits the moment the outreach campaign goes live.
A database that is '95% email-verified' in the vendor's metrics is meaningful only if it matches the buyer's CRM records at a comparable rate. Run a free match test: send the vendor a hashed list of 10,000 contacts from the CRM and ask them to return match counts and fill rates for the fields the buyer actually needs. The specific fields to measure:
The spread between 'vendor-claimed' and 'actual-match' is consistently in the 15–40% range; buyers who skip this step pay full price for a database that solves 60% of the problem.
Most B2B contact databases are priced per-seat with generous export limits that quietly encourage the buyer to make the data the center of every campaign. That's fine until the renewal, when the vendor discovers the buyer's usage and the per-seat rate goes up 3×. The right contract language caps per-user overages, guarantees price stability on renewal, and gives the buyer a right of termination for systemic data-quality failures — not just for non-payment. These are all reasonable asks; vendors who refuse them are telling the buyer what they think of the relationship. Teams whose contact data feeds identity resolution work need to be especially careful here — a mid-contract rate shock can upend the whole enrichment stack.