It is "common knowledge" that you cannot just record a telephone call without the agreement of the other party.
What about:
German law, §201 of the criminal code (in translation) says
(1) Whoever, without being authorised to do so, 1. makes an audio recording of the privately spoken words of another or ...
(2)1. uses a listening device to intercept the privately spoken words of another which they are not intended to hear
are in legal hot water. You apparently have in mind just recording your own voice, not that of "another". You can therefore record your voice. Recording the privately spoken words of another and then using a technological means to create a text is still recording a voice. Nothing in the law prohibits you attempting to write down the words of the other person, if you can write fast. I assume that you are intended to hear the conversation in the first place.
Section 201 of the German Criminal Code states that it is illegal to make an audio recording of the privately spoken words of another person without receiving authorization to do so.
What about recording only your own voice during the call?
There is no prohibition on recording your own voice.
What about using speech-to-text to write automatic notes of the call, but not storing a recording?
There is no prohibition on creating a text transcript of the phone call, whether it is done in real time or after the fact.
Neither is there a prohibition on any method used to achieve this, EXCEPT (without authorization) you are not allowed to record the person, transcribe their voice into text, and then delete the recording because you would still have made the recording.
Some would argue that real time voice-to-text technology violates this law, there is no output of this process that meets the definition of an audio recording.
There are several legal principles to overcome convict anyone accused of “making an audio recording” via voice to text:
EVIDENCE:
There would need to be an audio (sound, especially when recorded, transmitted, or reproduced) recording (the action or process of recording sound or a performance for subsequent reproduction or broadcast) introduced as evidence. If the prosecution was unable to provide a recorded, transmittable, reproducible sound as evidence for the court to consider, they would have to demonstrate via some other means that such a thing was made by the accused and existed at one time.
INTENT: (of the accused)
Making an audio recording is easy; if the accused intended to make an audio recording they would have simply done so. The very fact that they chose instead to create a written transcript rebuts any presumption that they intended to make and retain an audio recording of someone’s voice, and instead is compelling testimony that they were actually making a good faith effort to comply.
MENS REA:
Since creation of a written record of a conversation is not prohibited, and if there is no retrievable audio recording as an output of the method used, the accused would lack the mens rea to be found guilty of knowingly and intentionally violating the law that prohibits making an audio recording.
INTENT: (of the law)
The action prohibited by the law is "make", and only a natural person can be charged by a violation of the law. The law, as written, prohibits a natural person from making an audio recording. It is not intended to prevent a software application from momentarily accessing audio in the process of converting it to digital text.
