The one phone call is another one of the urban myths. You may or may not be permitted to use the phone. Generally, out of courtesy they will allow you to make one phone call. Often there are phones in the jail, and people can make as many phone calls as they want as long as there is somebody to accept collect charges.
Also heard in movies and TV-shows is the Miranda Warning (which is real):
You have the right to remain silent. Anything you say can and will be used against you in a court of law. You have the right to speak to an attorney, and to have an attorney present during any questioning. If you cannot afford a lawyer, one will be provided for you at government expense.
It stands to reason that if "you have the right to speak to an attorney", you should be provided with the means to do so (e.g a phone call).
And according to this it is indeed so:
An arrested person has the right, immediately after booking and, except when physically impossible, no later than three (3) hours after arrest, to make at least three (3) completed telephone calls. The calls are to be free if completed in the local calling area, and are at the arrestee's expense if outside the local area. The calls must be allowed immediately on request, or as soon as practicable.
From what I can gather the "one phone call" is not a myth perpetrated by Hollywood, but indeed a right.
So what's the truth?
And what's the "phone call" policy in other countries? Do their 'Miranda' rights include a free phone call?
Just to clarify:
I merely mention the Miranda Warning because I'm speculating the 'phone call' rule might derive from there. But my question is not about Miranda, it's about whether or not the law actually grants you the right to a phone call.