[Asterisk-Dev] SMDI and MWI: serial protocol for switch
communication
James Golovich
james at wwnet.net
Sat Jun 14 01:36:21 MST 2003
This could be easily implemented with an external app that connects to the
manager interface. Searching around on google it looks like some devices
support receiving the info over a tcp socket so that could be easily
handled as well. Handling the scenario of using something besides
asterisk for voicemail would require a few mods but it should be
managable.
I'd be interested in working on this, but I don't have any system to test
against.
As I was writing this email out and I decided to do some googling and came
up with a gpl'd smdi library. The home ftp site was down but I found it
on sunsite at ftp://sunsite.unc.edu/devel/lang/c++/smdi-0.0.3.tar.gz seems
to require APE-1.2.3.tar.gz from the same directory
I couldn't get APE to compile, but I didn't spend more than a minute on
it. But at least we should be able to gleam some info out of it
James
On Fri, 13 Jun 2003, John Todd wrote:
>
> I've been taking a brief look at how to integrate Asterisk's
> voicemail system with external voicemail systems. It is often the
> case that Asterisk is implemented in an organization that has prior
> hardware that they wish to maintain and simply use Asterisk as a
> "smart" call gateway or for VOIP routing purposes. Often, the
> voicemail system in Asterisk is a very interesting proposition as a
> replacement for expensive legacy platforms, but the question always
> arises: "Will the voicemail indicator lights on my current PBX system
> work if the voicemail is stored in Asterisk?" The answer is "No" or
> "Not unless we figure out some way to do it."
>
> Well, here is perhaps part of the answer on the "figure out some way
> to do it" question. It appears that MWI's can be lit with what
> appears to be a fairly simple serial protocol. Included below are
> two message snippets for the Bellcore spec on MWI transport, which
> I'm sure somebody clever could implement through a PC's serial port.
> These indicators are a part of a much larger simple protocol called
> "SMDI" which can be relayed via a serial port, but I will include
> only those messages for MWI.
>
> This protocol of course could be made to work both ways, if you want
> to have Asterisk-served phones show MWI for voicemail stored in some
> other voicemail system, so long as you have some sort of mapping
> table between extensions or the two systems have exactly the same
> numbering plan. This may be counter-intuitive, but never
> underestimate how emotionally attached people are to their voicemail
> systems.
>
> I don't have a particular need for these right now, because I've
> always had to answer "No" on the question of MWI, and those bids went
> to other vendors :( Perhaps if someone wants to beat me to the punch
> on a module to implement SMDI over a COM port, I can get my next bid
> that asks about it. It's also nice to throw useful stuff like this
> into the archives, because I'm sure someone will be looking for it in
> the next few months, and the actual specification is nice to have
> somewhere searchable.
>
> JT
>
>
>
>
> ----------------------------------------------------
>
> Following text from:
> http://digest.textfiles.com/TELECOMDIGEST/vol14.iss0251-0300.txt
>
> From: AL.FARNHAM at hq.doe.gov
> Date: 26 May 94 09:56:00 -0400
> Subject: Re: SMDI Question
>
>
> Here is the message format for an SMDI link between a switch and a
> Message Desk (Voice Mail System).
>
> The link is normally 1200bps full duplex without handshaking although
> some new implementations run at 9600bps.
>
> The Bell spec is TSR-TSY-000283.
>
> SMDI Message protocol:
>
> The system checks messages that it receives from the Message Desk for
> adherence to the following message protocols.
>
> Incoming messages - (Voice Mail System to Switch):
>
> There are two kinds of incoming messages the switch can accept
> from the message desk:
>
> OP:MWI(SP)nnnnnnn!(D)
>
> RMV:MWI(SP)nnnnnnn!(D)
>
> where: nnnnnnnnnn = station number (can be 7 or 10 digits)
> (D) = control-D (End Of Transmission) (SP) = space
>
> The first message activates the message waiting indication. The second
> deactivates the message waiting indication.
>
> For example, if Station B (DN 234-2000) forwards calls to the Message
> Desk and receives a message, the Message Desk activates message waiting
> indication for Station B with the following message:
>
> OP:MWI 2342000!(D)
>
> After Station B retrieves the messages from the Message Desk, the Message
> Desk deactivates message waiting indication for Station B with the
> following message:
>
> RMV:MWI 2342000!(D)
>
>
> Outgoing messages - (Switch to Voice Mail System)
>
> There are two groups of messages from the switch to the message desk.
>
> Call details - These message types give items of information concerning
> calls which the Message Desk received:
>
> (CR)(LF)MDgggmmmmannnnnnn(SP)yyyyyyy(SP)(CR)(LF)(Y)
> (CR)(LF)MDgggmmmmannnnnnn(SP)(SP)(CR)(LF)(Y)
> (CR)(LF)MDgggmmmma(SP)yyyyyyy(SP)(CR)(LF)(Y)
>
> MWI change failure - The request to change the Message Waiting Indication
> failed because it was either invalid (INV) or the switch
> unable to perform the change when requested (BLK).
>
> (CR)(LF)MWInnnnnnn(SP)INV(CR)(LF)(DL)(DL)(Y)
> (CR)(LF)MWInnnnnnn(SP)BLK(CR)(LF)(DL)(DL)(Y)
>
> where:
> (CR) = carriage return
> (LF) = line feed
> (SP) = space
> (DL) = delete character (ASCII value FF)
> (Y) = control-Y
> ggg = message desk number (001-063)
> mmmm = message desk terminal (0001-2047)
> nnnnnnnnnn = forwarding from station number (can be 7 or 10 digits)
> yyyyyyyyyy = calling station number (can be 7 or 10 digits)
> a = type of call
> where D = Direct Calls, A = Forward All Calls,
> B = Forward Busy Calls, N = Forward No Answer Calls
>
> For example, Station B (DN 234-2000) forwards all calls to the Message
> Desk. Station A (DN 678-1234) calls Station B and forwards to Message
> Desk number 002, terminal 009. The switch sends the following message
> to the Message Desk:
>
> (CR)(LF)MD0020009A2342000 6781234 (CR)(LF)(Y)
>
> Hope this information answers the question.
>
>
> Regards,
>
> Al
> ----------------------------------------------------
>
>
>
> ----------------------------------------------------
> Following text from somewhere in my mail archives:
>
> Message Waiting Commands
>
> The system accepts two commands for message waiting lights.
>
> OP:MWI[SP]xxxxxxx![Control D]
>
> RMV:MWI[SP]xxxxxxx![Control D]
>
> On: OP. This message will switch on the light for extension xxxxxxx. Leading
> zeros are stripped from the number prior to sending the number to the PBX.
>
> Off: RMV. This message will switch off the light for extension xxxxxxx.
> Leading zeros are also stripped from the number in this operation.
>
> The application should pad the extension to seven or ten digits using zeros.
> The system will accept a [CR][LF] at the end of the packet instead of the Ctrl
> D and the ! is optional. This allows installers to test the system by typing
> in MWI commands from a simple terminal or terminal program.
>
> For example:
>
> OP:MWI 0001234
>
> will turn on the message light for extension 1234.
>
>
> If the system carries out the request without an error, it will not respond.
> If an error is detected, a packet is sent back to the application with the
> following format:
>
> [CR][LF]MWIxxxxxxx[SP]aaa[CR][LF][Control Y]
>
> xxxxxxx This is the station identifier which encountered the error.
>
> aaa This is the error code. Two error codes are supported.
>
> INV This is a fatal error. The cause is usually that the
> extension number in
> the extension field does not exist.
>
> BLK This is a non fatal error. It usually indicates that an
> attempt was made
> to switch off a light that was already off.
>
> If the system has a queue of MWI operations pending then it discards any
> duplicate commands already in the queue - a command to put a light on followed
> by a command to turn a light off will be replaced by a single command to turn
> a light off.
>
>
> There is a special MWI command that can be given that always generates an
> error:
>
> OP:MWI[SP]5551212![Control D]
>
> This may be useful for testing.
>
> ----------------------------------------------------
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