app-sms.tex

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\section{Introduction}

   The SMS module for Asterisk was developed by Adrian Kennard, and is an
   implementation of the ETSI specification for landline SMS, ETSI ES 201
   912, which is available from \url{www.etsi.org}. Landline SMS is starting to
   be available in various parts of Europe, and is available from BT in
   the UK. However, Asterisk would allow gateways to be created in other
   locations such as the US, and use of SMS capable phones such as the
   Magic Messenger. SMS works using analogue or ISDN lines.

\section{Background}

   Short Message Service (SMS), or texting is very popular between mobile
   phones. A message can be sent between two phones, and normally
   contains 160 characters. There are ways in which various types of data
   can be encoded in a text message such as ring tones, and small
   graphic, etc. Text messaging is being used for voting and
   competitions, and also SPAM...

   Sending a message involves the mobile phone contacting a message
   centre (SMSC) and passing the message to it. The message centre then
   contacts the destination mobile to deliver the message. The SMSC is
   responsible for storing the message and trying to send it until the
   destination mobile is available, or a timeout.

   Landline SMS works in basically the same way. You would normally have
   a suitable text capable landline phone, or a separate texting box such
   as a Magic Messenger on your phone line. This sends a message to a
   message centre your telco provides by making a normal call and sending
   the data using 1200 Baud FSK signaling according to the ETSI spec. To
   receive a message the message centre calls the line with a specific
   calling number, and the text capable phone answers the call and
   receives the data using 1200 Baud FSK signaling. This works
   particularly well in the UK as the calling line identity is sent
   before the first ring, so no phones in the house would ring when a
   message arrives.

\section{Typical use with Asterisk}

   Sending messages from an Asterisk box can be used for a variety of
   reasons, including notification from any monitoring systems, email
   subject lines, etc.

   Receiving messages to an Asterisk box is typically used just to email
   the messages to someone appropriate - we email and texts that are
   received to our direct numbers to the appropriate person. Received
   messages could also be used to control applications, manage
   competitions, votes, post items to IRC, anything.

   Using a terminal such as a magic messenger, an Asterisk box could ask
   as a message centre sending messages to the terminal, which will beep
   and pop up the message (and remember 100 or so messages in its
   memory).

\section{Terminology}

\begin{itemize}
   \item SMS -
   Short Message Service
   i.e. text messages

   \item SMSC -
   Short Message Service Centre
   The system responsible for storing and forwarding messages

   \item MO -
   Mobile Originated
   A message on its way from a mobile or landline device to the SMSC

   \item MT -
   Mobile Terminated
   A message on its way from the SMSC to the mobile or landline device

   \item RX -
   Receive
   A message coming in to the Asterisk box

   \item TX -
   Transmit
   A message going out of the Asterisk box
\end{itemize}

\section{Sub address}

   When sending a message to a landline, you simply send to the landline
   number. In the UK, all of the mobile operators (bar one) understand
   sending messages to landlines and pass the messages to the BTText
   system for delivery to the landline.

   The specification for landline SMS allows for the possibility of more
   than one device on a single landline. These can be configured with Sub
   addresses which are a single digit. To send a message to a specific
   device the message is sent to the landline number with an extra digit
   appended to the end. The telco can define a default sub address (9 in
   the UK) which is used when the extra digit is not appended to the end.
   When the call comes in, part of the calling line ID is the sub
   address, so that only one device on the line answers the call and
   receives the message.

   Sub addresses also work for outgoing messages. Part of the number
   called by the device to send a message is its sub address. Sending
   from the default sub address (9 in the UK) means the message is
   delivered with the sender being the normal landline number. Sending
   from any other sub address makes the sender the landline number with
   an extra digit on the end.

   Using Asterisk, you can make use of the sub addresses for sending and
   receiving messages. Using DDI (DID, i.e. multiple numbers on the line
   on ISDN) you can also make use of many different numbers for SMS.

\section{extensions.conf}

   The following contexts are recommended.

\begin{astlisting}
\begin{verbatim}
; Mobile Terminated, RX. This is used when an incoming call from the SMS arrive
s, with the queue (called number and sub address) in ${EXTEN}
; Running an app after receipt of the text allows the app to find all messages
in the queue and handle them, e.g. email them.
; The app may be something like   smsq --process=somecommand --queue=${EXTEN}
to run a command for each received message
; See below for usage
[smsmtrx]
exten = _X.,1, SMS(${EXTEN},a)
exten = _X.,2,System("someapptohandleincomingsms ${EXTEN}")
exten = _X.,3,Hangup
; Mobile originated, RX. This is receiving a message from a device, e.g.
; a Magic Messenger on a sip extension
; Running an app after receipt of the text allows the app to find all messages
; in the queue and handle then, e.g. sending them to the public SMSC
; The app may be something like   smsq --process=somecommand --queue=${EXTEN}
; to run a command for each received message
; See below for example usage
[smsmorx]
exten = _X.,1, SMS(${EXTEN},sa)
exten = _X.,2,System("someapptohandlelocalsms ${EXTEN}")
exten = _X.,3,Hangup
\end{verbatim}
\end{astlisting}

   smsmtrx is normally accessed by an incoming call from the SMSC. In the
   UK this call is from a CLI of 080058752X0 where X is the sub address.
   As such a typical usage in the extensions.conf at the point of
   handling an incoming call is:
\begin{astlisting}
\begin{verbatim}
exten = _X./8005875290,1,Goto(smsmtrx,${EXTEN},1)
exten = _X./_80058752[0-8]0,1,Goto(smsmtrx,${EXTEN}-${CALLERID(num):8:1},1)
\end{verbatim}
\end{astlisting}

   Alternatively, if you have the correct national prefix on incoming
   CLI, e.g. using dahdi\_hfc, you might use:
\begin{astlisting}
\begin{verbatim}
exten = _X./08005875290,1,Goto(smsmtrx,${EXTEN},1)
exten = _X./_080058752[0-8]0,1,Goto(smsmtrx,${EXTEN}-${CALLERID(num):9:1},1)
\end{verbatim}
\end{astlisting}

   smsmorx is normally accessed by a call from a local sip device
   connected to a Magic Messenger. It could however by that you are
   operating Asterisk as a message centre for calls from outside. Either
   way, you look at the called number and goto smsmorx. In the UK, the
   SMSC number that would be dialed is 1709400X where X is the caller sub
   address. As such typical usage in extension.config at the point of
   handling a call from a sip phone is:
\begin{astlisting}
\begin{verbatim}
exten = 17094009,1,Goto(smsmorx,${CALLERID(num)},1)
exten = _1709400[0-8],1,Goto(smsmorx,${CALLERID(num)}-{EXTEN:7:1},1)
\end{verbatim}
\end{astlisting}

\section{Using smsq}

   smsq is a simple helper application designed to make it easy to send
   messages from a command line. it is intended to run on the Asterisk
   box and have direct access to the queue directories for SMS and for
   Asterisk.

   In its simplest form you can send an SMS by a command such as
   smsq 0123456789 This is a test to 0123456789
   This would create a queue file for a mobile originated TX message in
   queue 0 to send the text "This is a test to 0123456789" to 0123456789.
   It would then place a file in the \path{/var/spool/asterisk/outgoing}
   directory to initiate a call to 17094009 (the default message centre
   in smsq) attached to application SMS with argument of the queue name
   (0).

   Normally smsq will queue a message ready to send, and will then create
   a file in the Asterisk outgoing directory causing Asterisk to actually
   connect to the message centre or device and actually send the pending
   message(s).

   Using \verb!--process!, smsq can however be used on received queues to run a
   command for each file (matching the queue if specified) with various
   environment variables set based on the message (see below);
   smsq options:
\begin{verbatim}
   --help
   Show help text
   --usage
   Show usage
   --queue
   -q
   Specify a specific queue
   In no specified, messages are queued under queue "0"
   --da
   -d
   Specify destination address
   --oa
   -o
   Specify originating address
   This also implies that we are generating a mobile terminated message
   --ud
   -m
   Specify the actual message
   --ud-file
   -f
   Specify a file to be read for the context of the message
   A blank filename (e.g. --ud-file= on its own) means read stdin. Very
   useful when using via ssh where command line parsing could mess up the
   message.
   --mt
   -t
   Mobile terminated message to be generated
   --mo
   Mobile originated message to be generated
   Default
   --tx
   Transmit message
   Default
   --rx
   -r
   Generate a message in the receive queue
   --UTF-8
   Treat the file as UTF-8 encoded (default)
   --UCS-1
   Treat the file as raw 8 bit UCS-1 data, not UTF-8 encoded
   --UCS-2
   Treat the file as raw 16 bit bigendian USC-2 data
   --process
   Specific a command to process for each file in the queue
   Implies --rx and --mt if not otherwise specified.
   Sets environment variables for every possible variable, and also ud,
   ud8 (USC-1 hex), and ud16 (USC-2 hex) for each call. Removes files.
   --motx-channel
   Specify the channel for motx calls
   May contain X to use sub address based on queue name or may be full
   number
   Default is Local/1709400X
   --motx-callerid
   Specify the caller ID for motx calls
   The default is the queue name without -X suffix
   --motx-wait
   Wait time for motx call
   Default 10
   --motx-delay