Automating Bulk Messages

static public String createRandomNumberGroupId() {

Blob b = Crypto.GenerateAESKey(128);

String h = EncodingUtil.ConvertTohex(b);

return(h.SubString(0, 8) + '-' + h.SubString(8, 12) + '-' + h.SubString(12, 16) + '-' + h.SubString(16, 20) + '-' + h.substring(20));

}