1. SMS Module

Bogdan Iancu

   FhG FOKUS

   Copyright © 2003 FhG FOKUS
     __________________________________________________________________

   1.1. Overview

        1.1.1. Hardware Requirements
        1.1.2. Numbering Plan
        1.1.3. Address Mapping

   1.2. Dependencies
   1.3. Parameters

        1.3.1. modems (string)
        1.3.2. networks (string)
        1.3.3. links (string)
        1.3.4. default_net (string)
        1.3.5. max_sms_parts (integer)
        1.3.6. domain_str (string)
        1.3.7. use_contact (integer)
        1.3.8. sms_report_type (integer)

   1.4. Functions

        1.4.1. sms_send_msg_to_net(network_name)
        1.4.2. sms_send_msg()

1.1. Overview

   This module provides a way of communication between SIP network (via
   SIP MESSAGE) and GSM networks (via ShortMessageService). Communication
   is possible from SIP to SMS and vice versa. The module provides
   facilities like SMS confirmation--the gateway can confirm to the SIP
   user if his message really reached its destination as a SMS--or
   multi-part messages--if a SIP messages is too long it will be split and
   sent as multiple SMS.

   Errors occurred because of an invalid number or a too long message or
   because of an internal modem malfunction are reported back to the SIP
   user via a SIP message containing explanations regarding the error.

1.1.1. Hardware Requirements

   The SMS module needs a GSM modem to be able to send/receive the SMS
   messages. Usually, this kind of modems are externals, linked to the
   machine via serial cable. The modem can be a dedicated one (as the ones
   provided by FALCOM) or can be a GSM telephone that has an internal
   modem (as the latest mobile phones from NOKIA and ERICSSON).

1.1.2. Numbering Plan

   The gateway accepts and advertises phone numbers in international
   format, more specific like: +(international code)(area code)(number).
   Ex: Germany, D1 = +49 170 5678181 Romania, Connex = +40 722 123456 A
   number in this format is expected to be placed as username into RURI or
   in the To header. If RURI misses the username, the To header will be
   consider. Also, the gateway will advertise in this format the username
   in Contact headers (in SIP replies and requests) and in From headers
   (in SIP requests).

1.1.3. Address Mapping

   To identify the destination number of the SMS, the gateway expects to
   have a mobile number in username of the SIP destination address (for
   example sip:+401704678811@iptel.org). For the reverse direction,
   because the gateway has only one GSM number, the destination SIP
   address has to be encapsulated into the SMS body. The gateway expects
   to find a SIP address at the beginning of the SMS body in
   "sip:user.host" format. Everything before the SIP address will be
   discarded, the useful text begins exactly after the address (for
   example SMS="For sip:user@host hello world!!" -> SIP="hello world"),
   view configuration for disable this behavior (modems parameters 's' y
   't'). In order to facilitate replying, the gateway sends all the SMS
   messages with a header containing the source SIP address in the
   following format: "From sip:user@host (if you reply DONOT remove
   it)<new_line>". When an SMS-reply is received having this header (all
   of it or truncated at the end), the header will be left out (it will
   not be in the SIP message).

1.2. Dependencies

   The following modules must be loaded before this module:
     * tm - Transaction Manager.

1.3. Parameters

1.3.1. modems (string)

   Define and configure one or more GSM modems.
modems_value     = modem_definition *( ";" modem_definition )
modem_definition = modem_name "[" list_of_params "]"
list_of_params   = modem_param *( ";" modem_param )
modem_param      = name "=" value

   The following parameters can be used:
     * d=device (mandatory) - Device associated with modem (/dev/ttyS0,
       /dev/modem, etc.).
     * p=pin (optional) - SIM PIN - default is NULL.
     * m=mode (optional) - Modem working mode
       ("ASCII","OLD","DIGICOM","NEW"). Default value is "NEW".
     * c=SMS_Center (optional) - SMS center number for that modem. Default
       is the SMS center set on the SIM card.
     * b=baudrate (optional) - Default is 19600.
     * r=retry (optional) - How many times to try to re-send a SMS that
       reported error. Default is twice.
     * l=looping (optional) - Time for modem to wait before performing a
       new check for incomimg/outgoing SMS/SIP_MSG. Default is 20.
     * t=to (optional) - uri for sip header TO. Default is NULL.
     * s=scan (optional) - Values: 0: NOT SCAN uri from body sms, use URI
       in t=to. 1: SCAN uri from body sms (normal mode, default mode,
       clasic mode) 2: SCAN MIX (both modes), First SCAN Default is 1
       (SCAN).

Note

   No default value, the parameter is mandatory.

   Example 1. Set modems parameter
...
modparam("sms", "modems", "Nokia[d=/dev/ttyS1;s=0;t=sip:p-cscf@cidra.com.ar]")
modparam("sms", "modems", "Nokia [d=/dev/ttyS1;b=9600;m=new;l=30] ")
modparam("sms", "modems", "Nokia[d=/dev/ttyS1];Siemens[d=/dev/ttyS2]")
...

1.3.2. networks (string)

   Define and configure used GSM networks.
networks_value = net_definition *( ";" net_definition )
net_definition = net_name "[" list_of_params "]"
list_of_params = set_param *( ";" set_param )
set_param      = name "=" value

   The following parameters can be used:
     * m=msx_sms_per_call (optional) - Maximum number of SMS send /
       received from that net in one modem loop. Default is 10. This
       parameter was introduced to avoid starvation.
       Example of the starvation--a modem can send SMS for more than 1
       networks. If you have a huge number of SMS for the first network
       and the number of incoming SIP messages is equal to the sent SMS
       per same unit of time, the modem will never get to send SMS for the
       next networks.

Note

   No default value, the parameter is mandatory.

   Example 2. Set networks parameter
...
modparam("sms", "networks", "D1 [m=10] ;d2[ m=20]")
...

1.3.3. links (string)

   Define from which network each modem should send SMS.
links_value = modem_assoc *( ";" modem_assoc )
modem_assoc = modem_name "[" list_of_networks "]"
list_of_networks = network *( ";" network )

Note

   No default value, the parameter is mandatory.

   Example 3. Set links parameter
...
modparam("sms", "links", "NOKIA[D1;d2]")
...

   The modem NOKIA will send SMS from D1 and D2 net (in this order !). if
   in a net queue are more then max_sms_per_call SMS the modem will not
   sleep before starting the next loop ! Shortly, if messages are waiting
   to be sent, the modem will not go in sleep.

1.3.4. default_net (string)

   The default network to use. If no one specified, the first defined
   network is used. This parameter is useful only if the "sms_send_msg"
   exported function is used (see Section 1.4, "Functions").

   Example 4. Set default_net parameter
...
modparam("sms", "default_net", "D1")
...

1.3.5. max_sms_parts (integer)

   Shows in how many parts (SMS messages) a SIP message can be split. If
   exceeded, the SIP message will be sent truncated and the SIP user will
   get back another message containing the unsent part.

   Default value is 4.

   Example 5. Set max_sms_parts parameter
...
modparam("sms", "max_sms_parts", 10)
...

1.3.6. domain_str (string)

   Specify a fake domain name to be used by the gateway. The Contact
   headers and the From header from request will be construct based on
   this fake domain name. It's useful when the gateway is transparently
   hidden behind a proxy/register (located on different machines).

   Default is the name of the machine the gateway is running on.

   Example 6. Set domain_str parameter
...
modparam("sms", "domain_str", "foo.bar")
...

1.3.7. use_contact (integer)

   If a contact header should be added to the outgoing SIP messages. Even
   if the SIP draft forbids this, some UAS require it.

   Default is 0 (no).

   Example 7. Set use_contact parameter
...
modparam("sms", "use_contact", 1)
...

1.3.8. sms_report_type (integer)

   If the modem should ask for SMS confirmation from the SMS Center. If
   the SMSC reply with an error code, the gateway will send back to SIP
   user a SIP message containing the text (or part of it) that couldn't be
   send. Two report mechanisms are implemented:
     * 1 - the reports are delivered by the GSM device as SMS reports (so
       far supported only by Nokia modems);
     * 2 - the reports are delivered as async. CDS responses (supported by
       almost all modems, except Ericsson).

   Default is 0 (no report).

   Example 8. Set sms_report_type parameter
...
modparam("sms", "sms_report_type", 1)
...

1.4. Functions

1.4.1. sms_send_msg_to_net(network_name)

   Put the SIP msg in the specified network queue. The function return
   error if the number encapsulated into SIP message is malformed, if the
   content_type is incorrect or because of some internal failures.

   Meaning of the parameters is as follows:
     * network_name - Name of network.

   Example 9. sms_send_msg_to_net usage
...
if (sms_send_msg_to_net("D1"))
{
    if (!t_reply("202", "yes sir, SMS sent over"))
    {
        # if replying failed, retry statelessly
        sl_reply_error();
    };
} else {
    if (!t_reply("502", "Bad gateway - SMS error"))
    {
        # if replying failed, retry statelessly
        sl_reply_error();
    };
    break;
};
...

1.4.2. sms_send_msg()

   The same as the previous one, but use the default network queue.

   Example 10. sms_send_msg usage
...
if (sms_send_msg_to_net())
{
    if (!t_reply("202", "yes sir, SMS sent over"))
    {
        # if replying failed, retry statelessly
        sl_reply_error();
    };
} else {
    if (!t_reply("502", "Bad gateway - SMS error"))
    {
        # if replying failed, retry statelessly
        sl_reply_error();
    };
    break;
};
...
