Which AI phone assistant can waste a spam caller's time?

If you want an AI that keeps a spam caller talking instead of just hanging up on them, Secret Agent Voicemail is built for that: turn on spam detection, and calls from numbers not in your contacts get checked against a spam lookup. When a number scores above your threshold (70% by default), a spam handler answers instead of your normal greeting, and you pick which one: Quick Dismiss, Time Waster, Confused Elder, or Bureaucrat. Quick Dismiss politely rejects the call and hangs up. Time Waster pretends to be interested and asks endless questions, Confused Elder plays a sweet but confused elderly person with hearing problems, and Bureaucrat demands extensive verification and documentation before proceeding. People in your contacts always skip the check. Most built-in phone features work the other way around: Google's Call Screen asks who's calling and why and hangs up if the call is identified as spam, which is efficient but not entertaining. If stalling is the point, you need a tool that says so.

Screening and stalling are two different jobs

Screening means a machine picks up, asks a question, and decides whether to bother you. Stalling means the machine stays on the line on purpose, because every minute a scam operation spends on your fake grandmother is a minute it does not spend on someone who might actually hand over a card number.

Almost every assistant on the market does the first job. The second is rarer, and worth being precise about, because vendors describe it loosely. Here is what the cited pages actually claim:

• Google's Call Screen answers unknown calls, asks who is calling and why, and can hang up on spam callers. See Google's support page.
• Truecaller Assistant answers calls, asks the caller questions, detects spam, and tells you whether the call is worth answering.
• OsmO answers unknown numbers, asks the caller's purpose, and decides in real time whether to connect you, take a message, or block the call.
• Screendoor uses carrier forwarding to a private line where an AI answers unknown callers, blocks spam, and transcribes messages.
• Hiya AI Phone offers real-time scam detection, transcripts, call summaries, and synthetic voice detection.

None of those pages promise to keep a telemarketer on the line. If you want that behavior, look for it named outright as a feature, the way a spam handler personality is.

Free things to try before you pay anyone

A paid AI is not the first move for most people, and a blog that sells one should say so.

Register with the National Do Not Call Registry at donotcall.gov. It does nothing against outright criminals, but it cuts legitimate telemarketing, and it is free and permanent.

Turn on your carrier's free spam labeling. AT&T, Verizon, and T-Mobile all offer a no-cost tier that flags or blocks likely scam calls at the network level, before your phone rings. Call your carrier or check your account settings. This is the single highest-value free step.

Use Silence Unknown Callers on iPhone or the equivalent filter on Android. Calls from numbers not in your contacts go straight to voicemail without ringing. It is blunt and you will miss the pharmacy, but it works immediately.

Stop answering and stop talking. Answering a robocall confirms the line is live and raises the volume of calls you get. If you do pick up, saying nothing and hanging up is better than engaging.

Write the number down. If a caller claims to be your bank, the IRS, or a utility, hang up and dial the number printed on your card or bill. No legitimate organization objects to this. Keep a pen near the phone and note the date, the number, and what they claimed. If the calls are persistent and you think you are being targeted, that written log is what a lawyer or your state attorney general's office will ask for first, and complaints to the FTC at reportfraud.ftc.gov go faster when you have dates.

If you or a family member has already sent money, that is a lawyer conversation, not an app conversation. An AI that stalls callers does not undo a wire transfer.

Where a stalling voicemail actually fits

Spam handling is one feature of Secret Agent Voicemail, not the whole product. The service gives you a dedicated US phone number answered by an AI agent. Nothing gets installed on the phone you call from, so it works with landlines, prepaid phones, and smartphones. To have it catch the calls you miss on your own phone, you set up call forwarding with your carrier; the dashboard shows the codes.

For ordinary callers, the agent answers with your greeting in one of six voices (Adam, Brian, Mike, Serena, Jessica, Kim) and one of six personalities: Default, Jester, Comedian, Granola, Jaded, Karen. You can set one personality for everyone and override it per contact, so work callers and family hear different things. People in your contacts get greeted by first name. Messages land in your web dashboard with a transcript and the recording, and the transcript shows which personality took the call. You can turn on a text alert. Messages you do not save are deleted after thirty days.

There is a second half. Call your own number and say "Activate my Secret Agent," and the agent asks for your challenge phrase. The phrase is checked on the server, not by the AI, and you get two tries per call. Once you pass, the agent works for you: look up a contact's phone number, email, or address; text one contact a message you dictate; transfer your call to a contact or to any US number, such as a business it just found by web search; hear the reminders you saved; search the web; and, with Google Calendar connected, hear what is coming up and cancel or reschedule an event after you confirm out loud. Transferring the call ends the session. Anyone who does not know the phrase only reaches your voicemail.

That combination is the honest reason to pick this over a pure call screener. If all you want is fewer rings, your carrier's free filter will get you most of the way. If you want the spam calls handled with a Bureaucrat and also want a way to reach your contacts by voice from a borrowed phone, the two jobs sit on the same number.

What to check before you commit

Spam lookups are probabilistic. A 70% default threshold means some real calls from unsaved numbers may get the spam handler and some spam will get through to your normal greeting. Add the numbers you care about to your contacts, since contacts always skip the check, and adjust the threshold if it feels wrong in either direction.

Decide what the caller should actually hear. Quick Dismiss hangs up right away. The other three keep the caller talking, which is satisfying but means a live scammer hears a human-sounding voice on your line for a while.

Plans are $6.49 per month or $67 per year, both with every feature, and new subscribers get a 30-day free trial; details are on the pricing page. Test the spam handlers during the trial with a number you control before you decide. The rest of the mechanics, including how the challenge phrase works and what happens to your recordings, are in the FAQ.