Practical example · Telephony & Automation
Record calls after an announcement so no details get lost
Anyone who takes orders by phone knows the problem: the call was long, the notes are short. I built a phone system on a FritzBox that plays an announcement before recording, records the call and sends the recording and a text to your mobile.
- Phone system
- Asterisk 22 in its own container
- Line
- FritzBox, your existing number stays
- Result
- Recording and text on your mobile
- Monitoring
- Checked every minute, restart on failure
Principle
How it works
The FritzBox forwards incoming calls to the phone system. It answers, plays an announcement and then rings your phones. The call is saved as a voice file; after hang-up it arrives as a message on your mobile, followed by an automatically generated text.
Callers who do not want to be recorded are told another way to reach you in the announcement, for example WhatsApp or email. Missed calls are reported by email with time, duration and a ready-made callback text.
The announcement is spoken by a synthetic voice and says so. I agree the exact wording with your privacy notice.
Technology
Setup
- Phone system
- Asterisk 22 takes the calls from the FritzBox and records the conversation.
- Announcement
- The voice is AI-generated and greets by time of day; the text is tailored to your business.
- Text to read
- Local speech recognition turns the recording into German text. A translation is optional.
- Missed calls
- An email with number, time and duration, plus a prepared callback text.
- Monitoring
- A watchdog checks every minute that the system is registered with the FritzBox, restarts it if needed and reports it.
- Access
- The system only accepts connections from the FritzBox. Services run without administrator rights and credentials sit in separate files.
Measurement
What I checked
- Phone system
- Asterisk 22.9.0, running and registered with the FritzBox
- Monitoring
- Timer fires every minute, 2 minutes after boot
- Flow
- Announcement, recording, message to mobile, automatic text
- Missed calls
- Email with number, time, duration and callback text
Checked on 30 Sep 2026 on my own system. It runs as a normal user without administrator rights and only accepts calls from the FritzBox. I have not measured a comparison with other providers.
Test
What is still open
- Recognition accuracy
- The automatic text can make mistakes with dialect, background noise or technical terms. Always check key details such as amounts and dates against the audio.
- Your FritzBox
- Whether your line and model fit, I check before any quote. That is part of the free first call.
Limits
The legal framework, stated honestly
- Recording without consent can be a criminal offence in Germany (section 201 StGB). The German data protection authorities require the caller’s consent before recording starts; merely continuing to talk after an announcement does not count as consent there. Asking the caller to press a key is therefore the safer route.
- Whether and how you may record depends on your business. Please settle the announcement, privacy notice and retention periods with your lawyer or data protection officer. I supply the technology, not legal advice.
- Doctors, lawyers and other professionals bound by secrecy face additional rules. There I only record after written clarification.
- Recording staff calls for monitoring is a separate topic and not covered by this example.
For you
What this means for your business
Trades, practices, car dealers or offices: wherever orders and appointments arise on the phone, a recording to listen back to helps. I start with one number and the question which calls you really want to replay, and expand only when it pays off.
More on AI & Automation
Never forget an order taken by phone again?
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