DLR Callback

Getting the DLC for outbound SMS:

For DLR, the incoming format is as follows:

        "{\r\n"
        "  \"uuid\" : \"%s\",\r\n"
        "  \"time\" : %ld,\r\n"
        "  \"ani\" : \"%S\",\r\n"
        "  \"dnis\" : \"%S\",\r\n"
        "  \"dlr_stat\" : %d,\r\n"
        "  \"dlr_content\" : %S\r\n"
        "}\r\n",