Verification modes
Button captcha
A one-tap check right in the group: the newcomer taps the button and can start chatting. No response within 5 minutes — the account is removed automatically.
DM verification
The newcomer confirms in a private chat with the bot instead of the group, so service messages stay out of the feed. Available from the Basic plan.
How it works
User joins
New member attempts to join the group.
Challenge sent
CAPTCHA challenge is displayed to the user.
Verification
User completes the challenge.
Access granted
Verified users gain full access.
Customization options
Why CAPTCHA?
- First line of defense - Stop bots before they can even post.
- Reduce workload - Less spam means less moderation.
- Community quality - Better signal-to-noise ratio.
- Works with AI - Layered protection for maximum security.
Try the button captcha
One tap for a person, a wall for a bot script. This is the lightest of the verification types — and often all a group needs.
This is the exact button-press check a newcomer sees — try it.
How verification gates new members
When someone joins, Telm holds them at the entrance and sends a challenge — a single button tap in the group, or, in DM mode, a short check in a private chat with the bot: opening the chat or a simple arithmetic captcha. The account cannot post until it passes. With the in-group button, anyone who does not respond within five minutes is removed; in DM mode nobody is removed — unverified members simply stay muted until they pass, and the prompt in the group cleans itself up after three minutes, naming several newcomers in one message during a join surge. If a CAS check is enabled to run first, obviously flagged accounts are dealt with before a challenge is ever shown, so genuine joiners see the lightest step that still filters out automated joins. A failed check earns a ten-minute pause rather than an endless loop of fresh challenges.
The point of CAPTCHA is friction that a script will not bother with but a person clears in a second, which stops mass bot joins at the door and cuts the volume everything downstream has to handle. It is deliberately a first line, not the whole wall: a determined human spammer can tap a button just like anyone else, which is why the AI pipeline still reads what verified members actually post. Keep verification light unless you are under active attack — every extra step you add to slow bots also costs your real members a moment.
Frequently asked questions
Won't captcha annoy my real members?
New joiners solve one quick challenge once — a single button tap that takes a couple of seconds. Humans pass it without thinking; bots and mass-join scripts don't. Most communities see zero complaints and a dramatic drop in bot accounts.
What happens if someone fails the captcha?
They simply can't post until they pass. If they don't verify within the time window, Telm removes them from the group — they can rejoin and verify later. In DM mode, repeat no-shows get a temporary ban so they can't farm fresh challenges.
Does captcha stop bot raids?
It's the first line of defense: a raid of freshly-registered bots hits the captcha wall and can't post. Combined with the anti-raid shield — which detects join surges and locks the group down automatically — raids fizzle out before they reach your members.
Can I customize the verification?
Yes — choose where verification happens (a button in the group or the bot's private chat), write your own greeting text, and in DM mode set the time limit. A CAS check can run first, so known spam accounts never even see the challenge.
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