X++ code to validate Mobile no. in Ax 2012

static void MobilennoValidation(Args _args)

{

    boolean ret;

    #define.alphabets('ABCDEFGHIJKLMNOPQRSTUVWXYZ')

    #define.numbers('0123456789')

    int len;

    str  subst,keepnum;

    str Mobile;

    Mobile = "9876543210";

    len = strLen(Mobile);

    subst= substr(Mobile,1,len);

    keepnum=strkeep(substr(Mobile , 1, len), #numbers);

    if(len!=10)

    {

         checkFailed("@DMS1713");

    }

    else if((Mobile)&&(keepnum!=subst))

    {

         checkFailed("@DMS1678");

    }

    else

    {

        info("Mobile no, is validated successfully");

    }

}