YA Historical fiction old radio wartime parallel universe?

It has been like 10 years since I’ve even thought of this book so bear with me. I read it probably between 2005-2010.

Young adult book.

Vaguely remember the colors being orange on the cover.

Something about an old radio being found that connected the main character to either a parallel wartime universe or something like that. I believe it took place in Europe but can’t be certain.

He’d communicate with the radio to someone or something important to him.

I feel like there were maybe numbers involved in the title?

I feel like the entire cover looked like the ~40s radio

London Calling by Edward Bloor?

Omg thank you so much YES this is it. The relief i feel right now 😂