You’re on the right track, and yes, you can absolutely reach him.
Sending a letter
You can mail him at the address you have for FCI Pollock. Just make sure you include:
Without that ID number, mail can be delayed or returned.
You can also use InmateAid to type your letter online and have it printed and mailed for you.
Can he get mail “on the web”?
No. Inmates do not have internet access, so they cannot read messages online directly.
However, the Federal Bureau of Prisons uses an email system called CorrLinks:
How he can call you
Important tips
Bottom line
Write him using the correct address and his ID number, wait for him to invite you to CorrLinks, and set up your phone account so he can call once he is ready.