The first few days at Ouachita River are an orientation period, and understanding what that looks like helps set realistic expectations on both ends.
When an inmate arrives at a new facility after transferring from county jail, they go through intake processing before anything else. That means medical screening, classification review, property inventory, housing assignment, and an orientation to the facility's specific rules, schedules, and expectations. During that window, access to phones, commissary, and visitation is limited while staff get everyone sorted and settled.
That orientation period typically wraps up within a week. Once your brother in law clears it and is assigned to his permanent housing unit, phone access opens up along with the ability to add names to his visiting list and start using commissary.
On the phone question, most Arkansas Department of Corrections facilities operate on a prepaid system rather than collect calls. That means money needs to be on his phone account before he can make calls out. Collect calls are increasingly rare in state prison systems because the carriers have largely moved away from that model. Getting funds on his account as soon as he is processed in is the most practical way to ensure he can reach out quickly once phone access becomes available.
In the meantime, a letter through InmateAid sent to Ouachita River now ensures something is waiting for him when he gets settled. It lets him know you are aware of the transfer and ready to hear from him as soon as he can call.