Friend-assisted verification in WeChat, sent but not received.

It may be the following: 1, the SMS storage is full. The short message storage capacity of mobile phone is limited. If you don't clear the received SMS in time, you won't receive the follow-up SMS. It is recommended to delete the message and try again. 2. If your mobile phone is not turned on for a long time or in a place with poor signal for a long time, the short message sent to you will be invalid because it expires. Suggest to try another place; (The validity time of the verification string is: 20 minutes) 3. It is related to the local gateway. Due to the large number of local short messages in some time periods and the busy short message center, short messages may be affected, delayed or lost. I suggest you try again at another time later. 4. It is related to the SMS platform of the operator. There are individual failures (inconsistent orders)