August 27, 2026, 12:07 pm | Read time: 3 minutes
Many people think a phone call only begins when the person being called taps “Accept.” This often leads to complaints about customer service while waiting on a hotline or even gossiping about a friend’s partner while calling them. Researchers now report that the audio connection can be established before the receiver is picked up.
Called Parties Could Hear Sooner
According to a report by the Austrian news portal “ORF,” it can happen that the person being called hears what is being said on the other end several seconds before the call is actually answered. The caller usually assumes at this point that the connection has not yet been established, as the familiar ringing tone is still audible.
According to ORF, time frames of up to three seconds are possible. This does not mean that every phone call is affected. However, it is emphasized that this is not an isolated case but an effect that can generally occur in all mobile networks.
For callers, this is potentially problematic because they often feel unobserved during this phase. Many people talk to others in the room, share additional information, or comment on the situation while the phone is ringing.
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ORF asked Gernot Kubin from the Institute of Signal Processing and Speech Communication at TU Graz about the cause. According to Kubin, the way mobile networks transmit information is responsible for this effect. Voice data and connection setup information are handled via different transmission paths, which can lead to time delays. “Then it can be expected that perhaps a system component switches earlier and therefore the microphone is open,” explains Kubin.
In such cases, voice transmission can already start even though the ringing tone is still playing. The caller thus has the impression that the person being called cannot hear anything yet, while the connection is actually already partially active.
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The separate transmission of connection and voice data serves another purpose. This technology is used to transmit ringing tones, hold music, or automatic announcements such as “The participant is currently unavailable.” This way, callers receive feedback on the status of their call during the connection setup.
Special Caution with Hotlines
Consumers should be particularly attentive with call centers or service hotlines. According to the online magazine “Chip,” microphones can be activated before the actual conversation begins. In this way, information about callers could be captured even before the actual conversation.
The solution, according to Kubin, is quite simple: just remain silent until the conversation begins. “It would certainly be a recommendation if you want to avoid, so to speak, embarrassing situations.”
At the same time, it is not known how often such situations actually occur or under what specific conditions they are particularly likely.