v0.1, March 29, 2001
Copyright (c) 2001 Andres Seco Hernandez, AndresSH@alamin.org.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1
or any later version published by the Free Software Foundation;
with the Invariant Sections being questions and answers from 1 to 12,
with the Front-Cover Texts being "Alamin GSM SMS Gateway FAQ", and
with no Back-Cover Texts.
A copy of the license is included in the section entitled "GNU
Free Documentation License".
For help in using the gateway, send a message to a
alamin-user@lists.sourceforge.net.
You can find the website for the project at the URL http://www.alamin.org
To contact the developers of the project, send a message to info@alamin.org.
In general, a gateway is a program that allows systems using different data formats to connect to each other in as transparent a way as possible.
In an SMS message gateway, one end of the gateway is connected to a mobile telephone network, over which SMS messages are sent. The other end of the gateway can be connected to different systems or services. These most commonly include mail systems and IP networks.
]The main objective of the gateway is to send SMS messages from clients that do not have the necessary means, and to receive SMS messages to be processed or resent by some other means within the IP network.
Alamin is an implementation of the SMS message gateway. Written in Perl, its principle objective is ease of use, especially in its setup. Security and reliability are two other important considerations.
Alamin works by using three daemons that exchange messages via a spool, similar to an MTA (Mail Transfer Agent). Actually, it is an MTA for SMS messages.
On the IP network side of the gateway, at present only the SMSQP and SMTP protocols are implemented, but POP and IMAP implementations are anticipated.
On the mobile phone network side, extended AT commands are being used for communicating with GSM modems and calls to gnokii of the project of the same name for communicating with Nokia telephones supported by this project. In both cases, only the functionality of sending and reading SMS messages is used.
Alamin is also an old district of Guadalajara, a Spanish city close to Madrid. During the Middle Ages one of the areas was located outside of the walls of the city, along with one of its gates, the Alamin, topped by a tower which still stands today.
SMSQP stands for "Short Message Service Queue Protocol." It is a new protocol developed to connect to the gateway with clients from an IP network.
In September 2000 a request was made to IANA to reserve a TCP port to be used by this protocol. In October IANA reserved TCP port 11201 for this protocol.
The protocol is designed to manage short message queues waiting to be sent, as well as for making requests to send short messages and for removing those requests. It includes requests to report the status of the queue, GSM devices and gateway services.
The protocol has not been completely defined as of yet, since the definition is tied to the Alamin gateway project. You can check on its progress by reading the debugging logs generated by the core modules (GSGCMD) and the client (GSGC) of the Alamin project.
There are many applications that can use an SMS-to-IP gateway. Basically, the objective is to extend to the GSM network the functionality of client/server applications that currently run on IP networks, and to facilitate the access to various resources from mobile telephones that have the ability to send and receive short messages.
Some of the applications commonly used with other message gateways include banking services via GSM, SMS chats, information services of various types (betting results, traffic and weather reports, etc.), and information services for computer equipment.
By using applications that work through the gateway, Alamin gives access to any service capable of being based on a question-and-answer scheme by implementing IMPs (Input Message Processors) that analyze the message coming from a mobile telephone, act according to the message, and respond via the Alamin gateway client.
A computer to be used as the gateway server, a GSM device, and a way to connect the two.
As a GSM device, Alamin supports GSM modems that understand the extended AT command set and support text mode for sending SMS messages (PDU mode isn't supported at present, but there are plans to implement it) or Nokia telephones supported by the Gnokii project (http://www.gnokii.org).
Whichever GSM device you choose, you will need a connection cable to the serial port of the computer. If one isn't available, an infrared port in both the GSM device and computer is needed. Infrared devices are not recommended for permanent or working gateways due to high battery usage for the mobile phone and the rapid self-disconnect that some models use.
GSM modems should be used with transformers attached to some structure or wall. This will avoid problems with charging/discharging the mobile phone batteries as well as with instabilities caused by interference from the position of the GSM equipment with respect to nearby computers.
A page in the project website lists devices that have been tested and are compatible with the SMS-to-IP gateway.
A mobile telephone with GSM technology or GSM modem.
At present, Alamin uses GSM devices. With the coming of the new GPRS and UMTS networks, the necessary modifications will be added for new communications equipment.
The future of the SMS service appears to be guaranteed due to its widespread use. Even if the device used to access the mobile network changes, mobile telephone providers will probably make it a priority to maintain this service, which is what Alamin is based on.
Many mobile phone providers offer electronic mail gateway services to SMS messages free of charge. In many cases this service is deficient due to long delays, periods of unavailability, or even by limiting the number of messages per user and the days permitted.
Since you finally have GSM equipment connected to the gateway computer, and it is this equipment that sends the messages, these messages usually have a fixed cost on the part of the telephone provider. Once the volume of messages that will be sent is known, a price renegotiation with the provider is recommended to try to set it at an adequate level.
Some mobile phone operators permit direct IP access to their SMSC (Short Message Server Center). The cost to access this service should be analyzed, but for extremely large volumes of sent messages, it could be interesting. Alamin does not allow direct access by IP to the central short message server at present.
Each GSM device can have one way to connect. In any case, GSM modems are connected to the computer's serial port. Each mobile phone usually has a kit to connect to the computer. Read the documentation for your mobile phone or contact your service provider.
The following applies to version 0.3.6.
The gateway server was developed on GNU/Linux systems and is known to work on Solaris and BSD. In any case, there shouldn't be any problems with any Linux system that has Perl 5.004 or 5.005 and the following modules installed: IO::Socket, Net::hostent, Sys::Syslog and Digest::MD5.
You will need a free serial port, a GSM device that can connect to the serial port, a kit or data cable for the GSM device and its documentation, for making sure it is correctly connected to the gateway.
With regard to memory requirements, the three daemons that comprise the gateway require approximately 18 MB. Future versions of the gateway will be optimized to use less memory.
The consumption of processor time is very low when idle, since two of the daemons are waiting for TCP connections most of the time, and the third checks the GSM device periodically for incoming messages, with pauses between checks.
During periods of high load sending and receiving messages, CPU usage has been observed not to exceed 10 percent on a Pentium II 266.
If you expect a high level of utilization, you should anticipate a certain consumption of the spool and log directories /var/spool/alamin and /var/log/alamin.
The following applies to version 0.3.6.
The gateway's client program (gsgc) has few requirements. The only thing the client needs is an interpreter for Perl 5.004 or 5.005 with IO::Socket, Sys::Syslog and Digest::MD5 modules.
The client program was developed on GNU/Linux systems and is known to work correctly on Solaris and BSD. In order to use gsgc in Windows, you will need to install ActivePerl, the Digest::MD5 module, and patch the program to prevent it from using the Sys::Syslog module. There don't appear to be any implementations of this module for Windows. In the "otherOS" directory of the .tar.gz file, a client with this patch has already been created.
To equip it with greater ease of access when you don't find yourself near a computer.
Imagine accomplishing everyday tasks or do real work from any part of the world by means of a simple short message - fantastic - it's real and it works.
For your application to send messages, simply call the client, gsgc, with the appropriate parameters.
For your application to receive messages, implement a simple IMP (Incoming Message Processor) that will transform the message into something understandable by your application, or that invokes your application with the necessary parameters.
Version 1.1, March 2000
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