The condition for inactivity is non-use of paid communication services.
From 07.08.2017, the line "Daily payment of 3 rubles. With no consumption of chargeable services within 90 days" appeared on the tariffs without subscription fees.Voice mobile communication and sms (Post dvsof # 75221881)
If the number enters the financial blocking, then no later than the 10th day of the month following the month in which the balance reached the minimum write-off threshold, the Final Block is set on the number and the contract is closed by number.
Financial blocking - minus in the account or the amount is less than the amount of daily debit.
I will clarify that, in support of VIP clients, they voiced the period of being in financial blocking for up to 180 days and even longer. But the unequivocal NO about the possibility of closing the contract for the next month, after falling into a financial block, did not sound. So everything is at the discretion of the operator.
TP "Basic 092013"

The condition of non-activity is non-use of paid communication services or non-replenishment of the personal account.
In the absence of deductions for services / recharge of the personal account, within 120 days, the daily subscription fee begins to be charged. If the balance of the Subscriber’s personal account is found to be equal to or lower than zero within 180 (one hundred and eighty) consecutive calendar days, the contract for the provision of communication services shall be deemed terminated at the initiative of the Subscriber.

The list of actions that are considered "activity":

1. Any cash flows - payments, debits, adjustments.
   
2. Availability of active packages and options.
   
3. Incoming voice calls are received by you (for this, a phone with a SIM card must be turned on and registered on the network).
   
4. Incoming SMS delivered to you (for this phone with a SIM-card must be enabled and registered on the network).
   
5. Outgoing voice calls (except for calls to emergency services such as 112, 01, 02, etc.).
   
6. Outgoing SMS delivered to recipients (with the exception of SMS to our support service - SMS chat).

If none of these actions is performed within 90 days, the subscription fee of 150 rubles per month is included. When the balance is 0, the contract will be terminated, provided that the SIM card is still inactive (exceptions: The number is not purchased for money. The number is not transferred by MNP.)
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Cellular communication (Post froster_dandy # 79740010)
Cellular communication (Post by Lordwind # 70050587)
* 526 # - activation of the service: Banning of paid content numbers (a service for subscribers of the Ural branch of MegaFon PJSC. Valid only on the territory of the Ural branch)

* 984 # - ban content
At this time, when connecting to or switching to the TP of the Smart line, the Content prohibition service is automatically connected

The content personal account is connected when you personally contact the operator’s office or via the support service in Viber messenger.
* 160 # - checking the balance of the personal account.
Refusal of unwanted paid WEB-subscriptions
* 931 # - connect / check status
* 931 * 0 # - disable [/ COLOR]

Cancellation from SMS mailings from short numbers and alpha-numbering.
unsubscribe from SMS mailings from DEF-numbers(from standard numbers of mobile subscribers)
Ban on receiving informational SMS and SMS / MMS from the MTS websiteallows to refuse advertising informational messages of MTS and SMS, MMS from the site, as well as informational texts in service messages (for example, added to balance messages when requesting * 100 #)

To activate the service, and later add a number to Anti-Spam, you can send a free SMS to the number 345, in the message text you can specify a number or an alias that needs to be blocked. Federal numbers are indicated in the format 8ХХХХХХХХХХ. Non-federal numbers, such as + 4ХХХХХХХХХХ, + 700ХХХХХХХ, 8800ХХХХХХХ, etc., are indicated without a “+” sign.
To remove a number or nickname from the list - send an SMS to the number 345 with the text: 0 * [number to unlock]
To view the list of numbers added to Antispam SMS - send an SMS to the number 345 with the text: 1