A telephone booth is a small structure made out of metal, which can be a temporary haven if utilized properly.
The phone booth is a good place to use as a temporary base on long journeys. It should be used as a resting post at nightime, as clearing it will be very easy, and it is extremely simple to secure.
It should never be used as a permnant base unless you have backup. For example, if you are attacked by a horde of zombies, it is better to hide in the booth and to wait for your group to rescue you.
A telephone booth itself is too small to contain more than two survivors, so groups of survivors larger than 3 should ignore the booth. There usually isn't much to scavenge in the booth. The booth itself is made out of metal, and can survive a good 2 days of beating by a dozen zombies if properly secured. The booth provides little concealment, so one should expect to fight the zombies outside the booth sooner or later. The booth is small, so even 10 zombies can assualt all sides. Therefore, having a prolonged siege in a phone booth can drain morale.
It doesn't take much to secure a phone booth, just a bicycle lock. If the door is a "push" door, then you won't have to secure it, but if it is a "pull" door, then you will. Use the lock and attatch the door to a heavy and durable object, and the door will be just as effective as if it was push. If you tape some sheets at the walls, then the booth will no longer be transparent.