The size of a byte is typically hardware dependent, but the modern standard is eight bits. 8 bits can store 255 different values and this is enough to store one keyboard character. Therefore one byte can store one character of a text message.
There are many differences between bulk text messages and regular text messages. Regular text messages normally only go to one recipient while bulk text messages typically go to many.
Text messages can be stored on the SIM card and/or on the phone, depending on the type of phone.
It isn't clear how you would measure a text message in minutes. Normally, text messages have a length in characters - each character is probably 1 or 2 bytes. A byte, of course, is one millionth of a MB.
there are about 12356523025635485636 text messages sent every day
8 bits
It depends where the messages are stored ! If they're stored on the phone company's server - they will be deleted once the account is closed. If they're stored in the handset's memory - they'll still be available to be read - unless they were stored on the old SIM card.
i send 300 text messages in 1 day
For 2011, 2.30 Trillion text messages were sent in the US according to CTIA.
10
Almost a trillion
A byte order mark is a character indicating the endianness (byte order) of a string of text.
Data on a computer is stored in segments called bytes. Traditionally, 1 byte is equal to the amount of space used to encode 1 character of text. A kilobyte is 1000 (or 1024, depending on the standard being used) bytes.