Subscribing to Telephony Session Events is failing with SUB-410

I am subscribing to Telephony Session Notifications in my sandbox using this filter:

"/restapi/v1.0/account/~/telephony/sessions"

In the 'SubscriptionInfo' returned from the Subscribe the filter is in the collection of disabled filters, with the following text and error code.

Required application permission [CallControl] is missing
SUB-410

How do I set the CallControl permission in my sandbox ?