Select the cell(s) to format, Conditional Formatting, New Rule, Use a formula to determine which cells to Format. In the New Formatting Rule dialog in the field Format values where this formula is true, you write:

=$A$1>9999999999999

Press Format. In the Format cells dialog select the Number tab. Under Category select Custom and in the field Type, write "("###")" ###-#### ####. OK you out. Then in the Conditional Formatting Rules Manager press New Rule and repeat the process with next condition ($A$1>999999999999) and so on. Be aware that Excel cannot handle more than 15 digits as numbers.