I'm sorry, neither of those examples are correct. "Sorry, the number you dialed is busy. Please redial later." To dial a number means to enter the telephone number to begin a call. It is not the same as calling. When you get a recorded message, you have already dialed the number and that action is completed.

Sorry, the number (or subscriber) you dialed is busy now, please redial later. [ it's a past tense here, you dailed just now, you are not dailing, if you are dailing, you would not hear the voice.]

Seriously, learn to type properly. The number dialed IS busy. The number dialed = the number you have dialed Hence the "ed".

Hello Fanny: You are asking about a third party's use of a word. The plain fact is, they can be using the word in a grammatical error. The fact is, the recorded person can say dialing or dialed and either one can be correct, depending upon the context. If you have other information, you can explain further perhaps? --Warm Regards, Bruce