It is unusual to not be allowed visitation at all in TDCJ, even Death Row inmates can have visits.

I suspect that this will be because of a security lockdown at his unit, which may be just a small section of the prison - it doesn't have to be the whole prison. It is at the Warden's discretion whether inmates under security lockdown can receive vistis or not, and it is also not unusual for a whole wing to be placed on lockdown and restricted because of the antics of just one or two inmates.

Mail will run as usual, though may be a little slower if the mailroom is reading it more carefully for some reason (for example if it is a gang-related situation). Inmates will not be allowed to go to commissary at the start of a security lockdown, will not be allowed any recreational or educational activities and will be able to shower and exchange linen every 3 days. If inmates could call Europe, he would not be allowed to use the phones during a lockdown.

To check further, you could try putting his number into the eComm system. If it says "inmate can receive deposits only" then the chances are high that his part of the prison is on lockdown - unless you know that someone has already used his $50 allowance for this quarter.

If you want to check his location in the prison, start a Jpay email to him, then hit the Preview button, and at the top of the email it will give his housing location (eg C 3-18, which means wing C, row/tier 3, cell 18).