Phones are a symbol of how various aspects of the psyche seek to communicate with you. The person who calls you should be considered in terms of the adjective you would use to describe them - they can be representing a side of you seeking expression. The message that they share with you should also be considered as a message that may be coming from the Higher Self.
To dream that you are in a prison cell can portray feelings of guilt that are often unhealthy. Being arrested and locked away is the action of critical conscience which can sometimes undermine your need for authentic expression. A cell is a small space that doesn't allow for the expression of potential. Even a monk's cell can have associations with how spirituality has become Self limiting.
To dream of a cell as it relates to biology, you are examining the foundation how things grow. Something that you think is insignificant is actually contributing to the situation and may relate to the idea of survival.