The whole story might be fake, but I have watched some interviews on
YouTube (it is on Russian, but you can switch on subs if you want) with Russian hackers (
badb for example), that served sentence in US and they said it is possible to get a smartphone in fed prisons. It cost about $5k per phone. Especially it is easy if there are a lot of Italians in the prison, because they have their men everywhere and have a lot of money.
I have a strong believe, that if a prisoner have a lot of money, and with a current level of corruption, it is possible to get everything in cell.
Then there may be rare exceptions. Prison gangs are very active, even in federal prisons. And it is not just the Italians, but also the Latinos and East European gangs who are involved in this. For these gangs, it is easier to launder money, because they are trans-national, unlike the local gangs such as Aryan Circle or the Crips. And not all the federal prisons have the same level of security. For example, ADX Florence and USP Marion can't be equated to low-security prisons such as Marianna Federal Correctional Institution.