to this:
I seem to have come up with a way to check my smartphone for how much it holds a conversation from one charge.
You just need to call the MTS technical support.
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The real case of TPM. As if my sister had to turn off the service of unlimited internet on the phone (and forcibly connected by a caring operator). Called tech support, listened to classics for more than an hour, did not stand, went to the nearest MTS salon. On the question "How to call the operator?" she was told that she needed to call from the number of another operator. What would you think? She took the phone with the bandside operator, called the support of the MTS and was literally half a minute later communicating with a live support worker. This is how you care about your subscribers. Use it)