Phones are intrusive. You're sitting at your desk working well and it demands to be picked up. However, keep in mind that they generate callbacks. Procrastination is the inability to begin work. To overcome procrastination, look at its causes.
Procrastination is sometimes an expression of burnout.
It's a form of stress response. Learning to prioritize is the key to successful time management. By training yourself to distinguish between what must get done and what must get done now. If something has an urgent deadline, that probably becomes your most important priority. Then, order your list with the number two priority, etc.