I've written a couple of books that have been published (although they were in a specific and rather technical field -- not novels). I wrote the first one when I was 18, and my coauthor for it was 15. The chances of a good book being written by a young author are smaller, but it definitely can happen.
I'd recommend trying to demonstrate expertise to potential publishers. Contact them by email (instead of over the phone) and send an excerpt of your book. If you happen to have any writing qualifications, such as awards or published articles, mention those too. You could also try getting something small published first (like in a newspaper or magazine) in order to build up your credentials. In addition, no need to mention your age. Do you want their first impression of you to be that you're young, or that you write very well (assuming you do)?
For my first book, when we contacted our published we didn't mention our age. 396
We mentioned some credentials we had for the specific field we'd be writing about, and asked if they'd like to do a book with us. They replied asking for some sample work, and after we sent it they were happy and started the project. A little later we told them how old we were as it was necessary (they might have already known by looking us up though), but by this point it wasn't an issue.
Another option is self-publishing your book (I don't have experience with this though) -- your parents might be able to help, and I think there are services that can print your book in physical form. This kind of goes back to the tip about getting published a bit before trying to go to the next step with a novel accepted by a big publisher.
Finally, you might be a very good writer, but many people who think they're good aren't viewed this way by everyone else (i.e., people who might buy your book). So it's important to get feedback from other people. I don't want to say this due to you being young -- e.g., for myself, multiple people online have been skeptical of my books' quality just due to my age. However, by this point I know that I actually am a decent author, since my publisher has been extremely happy with my writing and the books are received quite well by people who bought and read them. But without this feedback, how would I know if it was just me assuming my books were good due to a subjective perspective? 396