In most cases this is not a parole violation, but the answer is not identical for every situation and it is worth getting confirmation before assuming you are in the clear.
Parole conditions in Texas are set by the Board of Pardons and Paroles and vary from case to case. Standard conditions typically restrict parolees from associating with people who have criminal records or are under criminal justice supervision, but family relationships are often treated differently than associations with unrelated individuals. A blood relative calling from prison is a different situation than socializing with former associates on the outside. That said, some parole conditions are written broadly enough that any contact with an incarcerated person could technically fall within a restricted category.
The safest move is a two-step check. First, read your parole conditions carefully and look for any language about contact with incarcerated individuals or people under supervision. Second, contact your parole officer directly and ask. That conversation protects you because you have documented that you sought guidance before proceeding. A parole officer who knows you asked in good faith is in a very different position than one who discovers contact was happening without disclosure.
On your brother's end, it is worth having him check with his case manager or unit staff as well. Calls from inmates to parolees are sometimes flagged in the phone system, and while it is unlikely to create a serious problem, an undisclosed connection between an inmate and someone on supervision can draw scrutiny that neither of you needs right now.
A quick conversation with your parole officer costs nothing and removes all of the uncertainty.