I would like to subpoena text messages from a cellphone that is under my name that my husband uses. Does he have to know?
Generally, in order to obtain subpoena power, you would need to file a lawsuit and have your attorney draft a subpoena to the cellphone provider. Since your question sounds like it is a family law situation, you would most likely need to file a divorce petition.
Alternatively, you could hire a PI who, operating under the laws of the State of Texas, could obtain information pertaining to the texting.
Here are a couple of links: