function check_phone(phonenum1, phonenum2, phonenum3)
{
    switch (phonenum1.value)
    {
        case "02"  :
            break;
        case "031"  :
            break;
        case "032"  :
            break;
        case "033"  :
            break;
        case "041"  :
            break;
        case "042"  :
            break;
        case "043"  :
            break;
        case "051"  :
            break;
        case "052"  :
            break;
        case "053"  :
            break;
        case "054"  :
            break;
        case "055"  :
            break;
        case "060"  :
            break;
        case "061"  :
            break;
        case "062"  :
            break;
        case "063"  :
            break;
        case "064"  :
            break;
        case "080"  :
            break;
		case "010"  :
            break;
        case "011"  :
            break;
        case "016"  :
            break;
        case "017"  :
            break;
        case "018"  :
            break;
        case "019"  :
            break;
        case "0502" :
            break;
        case "0505" :
            break;
        case "0506" :
            break;
        default     :
   			alert("국번이 잘못되었거나 입력하지 않으셨습니다");
			phonenum1.focus()
   			return false;
    }

    var chg_num1 = "";
    var chg_num2 = "";

    for (var i=0; i < phonenum2.value.length ; i++)
    {
        var str_dig1 = phonenum2.value.substring(i,i+1);
        if (str_dig1 >= "0" && str_dig1 <= "9" )
        {
            chg_num1 = chg_num1 + str_dig1;
        }
    }

    for (var i=0; i < phonenum3.value.length ; i++)
    {
        var str_dig2 = phonenum3.value.substring(i,i+1);
        if (str_dig2 >= "0" && str_dig2 <= "9" )
        {
            chg_num2 = chg_num2 + str_dig2;
        }
    }


    if (chg_num1.length < 3 || chg_num2.length < 4){
		alert("전화번호 자리수를 다시 확인하여 입력해주십시오");
        phonenum2.focus()
		return false;
    }

    if (phonenum1.value == "0505")
    {
        if (chg_num1 < 4) {
   			alert("전화번호 자리수를 다시 확인하여 입력해주십시오");
   			phonenum2.focus()
   			return false;
        }
    }

  	return true;
}