To make it simple, I do it one of two ways.
The first is to summarize the text in prose form. This would be like "He sent her a text message asking her to come over."
The other way is script format. For example:
Jane: Where are you guys?
Tom: Can't find my keys.
Fred: What time were we meeting?
Jane: 7
Jane: Hurry up, guys.
The way I label the characters' names depends on the story. For example, in my comedy series, the texts are labeled with puns based on their name. Other stories, I just use their first names or their first initial and surname.