Android P will be adding support for a call recording tone so users on certain carriers will be aided in recording phone calls lawfully, according to a series of recent commits. This is not native support of call recording being added to Android P which already exists but is not implemented by most OEMs. This is simply so that a user on the other end of a phone call can be made aware the phone call is being recorded, and will only be enabled if the carrier wishes the device to play the tone.
The tone is a 1400Hz note that will play every fifteen seconds if the carrier enables it. It works by detecting the package name of a call recording app using the previously linked API. If any such package is detected, then the outgoing call will have the tone played to warn the other end that their call may be recorded. The tone will be automatically played depending on carrier configuration, which is determined by the SIM card.
According to the commits, Vodafone Germany is the only carrier that this call recording tone support will be mandated (for now), as the MCC/MNN combination mentioned in one of the files matches Vodafone’s carrier identity: 26202. This was likely done because Germany is two-party consent when it comes to call recording, not one party like some other countries. This means that the person on both ends of the phone line needs to know that they are being recorded, and calls may not be recorded without each party’s consent.
It may come as an annoyance to those on the receiving end of such a call, as there doesn’t seem to be any way for a user to disable it even if they know they are actively being recorded. If it becomes an issue, it’s likely that the rooting community will find a way around it as it is seemingly just a small Android system change. Those worried about the addition won’t have to worry for a long time, as it’ll only work in Android P and only with certain carriers that mandate it.
We feel that this will be a welcome change, however, as it will help users ensure that they are abiding by the law and also help users on the other end know that their conversations could be recorded. According to the developer of the popular call recording software BoldBeast Call Recorder, the ability to play a tone through a phone call was not possible until this change. Perhaps the rooting community can also enable this call recording tone on all phone calls for users who want to proactively alert other users that they may record a conversation.