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@sidomain.net). 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") 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).

1.2.1. OpenSER Modules

The following modules must be loaded before this module:

• tm - Transaction Manager.

1.2.2. External Libraries or Applications

The following libraries or applications must be installed before running OpenSER with this module loaded:

• None.

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.

No default value, the parameter is mandatory.

...
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.

No default value, the parameter is mandatory.

...
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 )

No default value, the parameter is mandatory.

...
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).

...
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.

...
modparam("sms", "max_sms_parts", 10)
...

1.3.6. domain (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.

...
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).

...
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).

...
modparam("sms", "sms_report_type", 1)
...

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.

This function can be used from REQUEST_ROUTE.

...
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();
	};
	exit;
};
...

1.4.2. sms_send_msg()

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

This function can be used from REQUEST_ROUTE.

...
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();
	};
	exit;
};
...