Once a caller starts talking, Kollie resolves or routes 94% of inbound calls. The biggest remaining lever is the first 15 seconds of the call.
8 min de lecture
These figures come from 7 of our highest-volume deployments over the last 90 days: about 16,000 calls and 16,300 minutes, in Dutch, German and French.
93.9%
success rate when the caller engages
82.5%
success rate across all inbound calls, including the ~12% who hang up during the greeting
29%
success rate on outbound calls, held back by voicemail and IVRs
70.7%
of inbound calls arrive outside business hours (Mon-Fri 09-17)
299
emergencies captured, 63% of them outside office hours
78 sec
average length of a successful call
Results by use case
Inbound deployments with one clear job (routing, fault intake, after-hours cover) reach 84% success. Outbound calls land at 29%, mostly because of voicemail, IVRs and people who never pick up the conversation.
Deployment
Direction
Calls (90 days)
Success
Success once caller speaks
Hang-ups before speaking
Transferred to a human
Insurance broker (NL), AI receptionist
Inbound
5,752
91%
96%
3%
85%
Lift maintenance (DE), fault intake
Inbound
1,061
87%
98.5%
11%
30%
Sewer & drainage services (NL), fault intake
Inbound
855
82%
94%
9%
9%
Home care provider (NL), after-hours line
Inbound
4,020
75%
90%
16%
43%
Housing association (NL), general line
Inbound
764
58%
85%
31%
1%
Construction site security (NL), outbound alerts
Outbound
1,237
33%
48%
24%
1%
Insurance application document collection (NL)
Outbound
887
25%
52%
32%
0%
"Success" means the call ended in a real outcome: routed, issue logged, information given, callback or appointment captured. A call that ended as incomplete or a wrong number counts as unsuccessful.
Six patterns behind successful calls
1Keep the opening line to about 100 characters
Almost every failed call ends within the first 15 seconds: only 0.5% of calls under 15 seconds succeed, compared with 84% at 30–60 seconds and 96% at 2–4 minutes. The opening that works best is name, company and one open question:
"Good afternoon, you are speaking with Tess, the AI assistant of [company]. How can I help you?"
With that greeting only 3.6% of callers hang up silently.
Longer opening lines lose more callers before they speak
Inbound deployments, last 90 days: share of calls where the caller hung up without saying a word
Kollie call logs, 5 inbound deployments, late July to October 2026
The housing association's 240-character opening includes a recording notice and a message for agencies, and it loses 31% of callers. One deployment also tested two greetings: the 83-character version lost 6% of callers and a longer variant lost 18%.
2Give the bot one clear inbound job
The top three deployments each do one thing: route calls to the right person, or take in a fault report. Once the caller is talking, they succeed 96% of the time. Outbound calls get stuck on voicemail and IVRs before any conversation starts.
3Ask a triage question first
The lift maintenance bot opens with "Is someone trapped in the lift, or is it a technical fault?" That one question sets the path for the rest of the call. With callers who engage, it succeeds 98.5% of the time, even though calls average 2 minutes and 9–10 turns.
4Combine live transfer with structured data capture
Every deployment above 80% success can both capture the caller's details and hand over to a person live. The housing association has neither, and it left 239 callback requests for staff to follow up in 90 days.
5Connect a system so the bot can finish the job
The sewer services bot looks up the caller's address through an integration. As a result, only 9% of its calls need a human, and 94% of engaged calls succeed.
6Sell it as after-hours cover
71% of inbound calls arrive outside office hours, and the bot answers every one of them. 188 of the 299 emergencies reported came in after hours, when no one would otherwise have answered.
Checklist for a high-performing deployment
The best deployments in this data tick nearly every box. Use this list when scoping a new customer or reviewing a reseller's setup.
Opening line under ~100 characters: name, company, "How can I help?"
Live transfer configured for each department or on-call number
Legal or recording notices moved after the caller's first answer, or shortened to one clause
Structured data capture (name, address, issue) sent to the team or system
One clearly defined job per bot (routing, fault intake, after-hours line)
At least one lookup or integration, so the bot can finish common requests alone
A triage question first when urgency varies (emergency vs routine)
Live 24/7, with emergencies routed to on-call staff after hours
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