Notice how many times he calls you and the reasons behind his calls. If he hardly calls you and does not answer your phone calls, chances are he is a guy who is not ready for a relationship.
Ask him how he feels about seeing other people. If he tells you it is not okay but seems hesitant, then ask him how he feels about relationships. If he tells you that he has not thought of it or he is not ready for it now, then he is not serious about you.
Ask yourself if every interaction when he calls or takes you out leads to sex. If that is the case, he is using you and will never commit. This shows that he can have sex with you and have no feelings for you. A guy like this is hard to change.
Judge him by his actions and not his words. A guy who talks about his family and friends a lot seems like a guy who likes to share. Consider how many times he actually took you to meet his family or friends. If he has not, then he is not ready for a relationship.
Consider if he makes plans for the two of you to go out. A guy who cares about you will not sit and wait for you to make plans. Do not ask him to do something all the time. If he does not initiate it, then he is a guy who is ready for a relationship.
Give him the keys for your place and ask him for his. A guy who is serious will not mind exchanging keys. A guy who refuses to do so is someone who is hiding something, and chances are he is not ready for a relationship.