User assigned to single group can only view the ontacts

1. Under Drupal > Administer > access control > roles, create a role for single group adminstration.
2. Under Drupal > Administer > access control > permission, select the view/edit for any one group.
3. Create a user and assign it the above created role.
4. Login using the newely created user.
The user can only view the contacts but cannot edit them. He can also view the contacts that are assigned to other groups