Translation:My telephone number is 1234.
In case anyone's wondering, 号码 ("hoa ma") basically means the "number" part for the phrase "phone number".
It's better to say the full phrase 电话号码 ("dian hua hoa ma") because it is more commonly used and translates directly to "telephone number", and there is no doubt to the listener whether you're referring to a "phone" or a "phone number".
That being said, saying 电话 for "phone number" isn't wrong if the listener/reader deduces it from the situation or context.
Also there are a few other variations of Chinese characters that translate into the word "number", such as 数 ("shu") and 数目 ("shu mu"). But you can't say 电话数目 ("dian hua shu mu"). These characters are only used in a "mathematical" sense.
Not strictly true. In many languages you can just say "phone", including Chinese. You can say it in Spanish too. "Mi teléfono es 1234" (at least in Central America, I don't really speak with people outside of there).
I don't think I ever hear old people say just "phone" in either Chinese or Spanish though.
They are parts of a single word; 話 (hua; I can only type traditional characters here) by itself just means speech/talking and wouldn't be understandable as "telephone" or "telephone number". The tien part (電) means electric/electronic (or "lightning") and also couldn't mean phone number by itself, though it's conceivable as a written abbreviation.