After you get to know each other, and only if you can afford it, you may consider asking the prisoner to call you. Just as the mailing address, and every thing else involved in support work, consistency is always a great advantage. Offer a reliable phone number and suggest convenient times for them to call. Having that direct line of communication is more expedient than a dialogue through mail. Details of support work can often be discusses more easily through phone communication.
Different prisons have different restrictions on calls.
Some control unit prisons offer extremely limited phone time, and this may prevent this form of connection from occurring. However, some prisoners have better opportunities to use the phone and may enjoy the chance to have a more direct form of communication with their supporters. Conditions of phone usage vary from prison to prison. Some are allowed only to make collect phone calls, others are required to pay for all of their own calls. Some offer both.