My friend changed his telephone number. I know his mobile provider and the type of phone he has. Is there any way to find out what his new number is secretly?

How about asking them, as it's the only way that will work for you.

Did he change his number so you (and others) won't call him? Like Curlyben said, the only way is to ask him.

My friend changed his telephone number. I know his mobile provider and the type of phone he has. Is there any way to find out what his new number is secretly?

Why "secretly"?

I agree with the others. If he is a friend, you should be able to ask him. If you are attempting to find his new number without his knowledge then it sounds like you aren't friends at this point in time.

I agree with the others... ask him... if he wants you to have it, he'll give it to you. Otherwise you aren't going to find it.

I'm guessing since you want to do this secretly.....this so called friendship is completely one sided.

Short answer: no.
Thankfully! Someday it might be YOU changing your number to avoid certain people. Creepy to try, right?? RIGHT?

I have just one word for you; Stalker! Know what it means?

Of course you are not a friend, I have no idea who you are to this person, but if they were a friend,
1. you would not have to do it secretly
2. you could just ask them
3. should have their Facebook or email to contact them