Well, when you're in a magical prison you don't have a magical pay phone to make a magical 5-minute call.
That... is just crappy writing. Going to add this to the list of "Why the Shards needs a revamp".
In fairness, you can't really call it crappy writing. The writing was all done well before anyone had the 'call' option, well before the idea of adding that in as a QoL feature was even around. It was bad editing/oversight when adding the 'call' option in. They should have reviewed the TF, saw that the contact is making long range contact already, and just added a 'call' option for him.
That... is just crappy writing. Going to add this to the list of "Why the Shards needs a revamp".