V Netcom SMS can't be received! Voice verification code can't be received either! What's going on here?

You can find the reason, 1, the memory of the mobile phone is full and needs to be cleaned. 2. The network signal is unstable and the reception is delayed. 3. The service provider's software and hardware are unstable, the arrival rate is not high, and the loan is not enough. 4. Contact Yimei customer service for consultation. 5. Change the service provider and choose a better one.