IIRC, Subie said he looked into this avenue & was advised that T-Mobile dumps all information after 24-48 hours. Said information is likely the key to finding some answers & quite possibly Jenna!!
I'm unsure who Subie spoke with but, I don't buy the info he was told.
Per the linked article, T-Mobile's 'retention' is as follows:
LINK:
https://articles.forensicfocus.com/2017/04/18/cellular-provider-record-retention-periods/
I wonder if Subie made a general customer inquiry to T-Mobile's customer service. If so, it could explain the information he received.
If T-Mobile knew the circumstances, I'm almost certain they would have advised him differently; however, I would expect a warrant would be required before T-Mobile began the process of compiling all information related to Jenna's phone.