For all the phone interviews I have done for an entry level programmer they usually ask you some basic questions about concepts in general, features in your language, your background with other technologies, and some behavioral questions.
From my experience they usually last about an hour and usually consist of drilling in you a variety of areas covered below. If you know when your interview will take place, I recommend you have the area cleared of all distractions (kids, loud noises, cellphone). I also recommend if you get nervous being put on the spot, print out some practice questions and have a friend or family member practice drilling you on those questions.
What is a class, interface, abstract class, inheritance, polymorphism,encapsulation ... etc.
Can you name a design pattern and when you would use it?
What is the difference between merge sort and quick sort? What is Big 0 notation?
Language specific questions:
What is a delegate?
Can you tell me how many bytes an int uses?
Can you tell me what keyword X does in this language?
How do you go about solving problems? Do you brute force it or do you Google it?
Do you like working alone or with a team?