A sales qualified lead is a lead that a salesperson has spoken to and confirmed against qualification criteria, typically some form of need, authority, budget and timing. It is the grade at which forecasting starts. SQLs close at 15 to 30% in most B2B teams, against 1 to 5% for marketing qualified leads, because a human has checked the fit rather than a scoring model.
An SQL is defined by a conversation, so the measurement is the qualification call and its notes. Frameworks such as BANT, MEDDIC and CHAMP give that call a structure; the lead qualification guide compares them. The ratio of MQLs to SQLs, often 10 to 20 percent, is the handoff metric marketing and sales argue about most.
Reachability is usually settled by the time a lead is sales qualified, because someone has spoken to them. It comes back as a problem three to six months later when the deal stalls and the champion has moved jobs; B2B addresses decay at the rate measured in BounceZero's decay study (only 19.2% of addresses still valid 90 days after a check), so stalled SQLs are worth re-verifying before re-engagement.
A team receives 300 MQLs, qualifies 45 as SQLs and closes 11. The MQL to SQL ratio is 15%, the SQL close rate 24%. If the 300 MQLs had been verified at entry and 20 unreachable records removed, the sales development reps would have spent 7% less time on calls that could not connect, without changing the 45 or the 11.
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Verify Leads - FreeAyoub built BounceZero's 5-stage validation pipeline, its dedicated BGP-announced IP infrastructure, and the Patroni HA PostgreSQL cluster behind every verification. Previously built high-volume email delivery infrastructure. Trained at 1337 Benguerir (École 42 network, 2019). Open-source: bgp_analyzer.