I think we need more context. What You understand literateray is correct but for me it has no sense. I understand: Somebody/He/She took the phone accidentally. LO is a pronoun. As you understand the sentence... is the object or what the cellphone took. As I understand the sentence, is the cellphone too.
we don't use that much ' llevar ' , but a phrase with it will be • debes de llevar un abrigo ( you must take a coat with you ) • el no suele llevar las llaves ( he usually don't take the keys with him )
we usually use diferents forms of the verb llevar like ' llevate ( context = you have to take ) , llevemos ( context = we have to take ) ..."
llevarse can be used with all persons = yo llevo ( I take / carry ) tú llevas ( you take / carry ) él /ella lleva ( he/ she takes/carries ) nosotros llevamos ( we take / we carry ) vosotros llevais ( you take / carry ) ellos / ellas llevan ( they take / carry )
this is the present but they are diferent words for each situation .
If you want to know how to say any phrase , and what yo use in each one , you can ask me