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So if you have two phones in your hand and call the other phone and cant hear yourself on the other phone then you walk away from the other phone you can hear yourself on both phones, what causes that?

Hi @scheiderichv , Sounds like there may be some sort of automatic audio feedback suppression in operation. Audio feedback occurs when the there is a sound loop between the audio input and the audio output which if left unchecked causes a howling sound to be generated, like what is heard sometimes when a microphone is used too close to the speaker on a stage. It won’t happen if you’re on two different calls on the phones and holding both, because the phones aren’t connected to each other. What is the make and model numbers of the phones?