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7-05-01
Build a Caller ID Application (Part 2) by Erick Tejkowsi
Last week we talked about the hardware requirements for
completing a REALbasic Caller ID project. This week, we'll discuss the Caller ID
specification, learn about the REALbasic Serial control, and begin building the project. By the end of this
lesson, you should have the basic knowledge to begin working on a Caller ID application.
The Caller ID Specification
Before jumping into the code for this tutorial, it would be a good idea if we took a brief look at how Caller ID works.
From here on out, I will refer to Caller ID as CID.
On enabled telephone systems, CID information is sent to you
sometime between the first and second ring of a phone call. The data comes to you as a string of characters. The idea of this
project is to receive this string of data and pull out the desired information (the phone number and the caller's name).
The CID string of data begins with the text:
MESG =
(Note that there are spaces before and after the equals sign.)
The next character in the string denotes which type of CID data follows.
There are two possible formats for CID data:
- SDMF - Sends the phone number (only)
- MDMF - Sends the phone number and other data (usually the name)
To simplify this tutorial, we will only discuss the MDMF format. SDMF works in much the same way as MDMF, but it is more simplistic,
so adding this
functionality later shouldn't be tough. When the data is in MDMF format, a Chr(128)
follows the "MESG = " string discussed earlier. For SDMF, a
Chr(4) follows instead.
The next character in the CID string represents the length of the remaining data. Following the length, is the date of the call and the
name and phone number of the caller. The date, name, and phone number are each preceded by a data type and length of that data.
The possible data types are:
- 1 = date
- 7 = name
- 2 = phone number
For a technical description of the CID specification,
see this link.
Okay, enough of these boring specs... Time to code this project!
Building the Project
The REALbasic Serial control (pictured below) permits you to send and receive data through the serial port of your Mac. This is how
we will capture the CID data. To use the Serial control, simply drag it from the toolbar and set its properties in the Property window.
For now, you can leave the default settings as is.
In addition to the Serial control, add the remaining controls to the interface:
| RB Control | Name |
| PushButton | StartButton |
| PushButton | StopButton |
| StaticText | labeltype |
| StaticText | labellength |
| StaticText | labeldate |
| StaticText | labelname |
| StaticText | labellabelphone |
| PopupMenu | PopupMenu1 |
By now, your interface might look something like this:
Next, open the Code Editor and place the following code in the Open event of PopupMenu1.
me.addrow "Modem"
me.addrow "Printer"
me.listindex=0
Proceed to the Action event of StartButton and add this code:
dim connected as boolean
Serial1.port = PopupMenu1.listindex
connected = Serial1.open
if connected then
Serial1.write "AT#CID=2" + chr(13)
StopButton.enabled=true
me.enabled=false
else
msgBox "There is a problem connecting to the current serial port."
end
This code starts off by assigning a port to the Serial control. Normally, this is either the modem or the printer port. Next, the
code opens the serial port. If a connection is made, the code then sends a command to the Serial control. The command is:
AT#CID=2
and it tells the modem to make its Caller ID function active.
Once the Serial control has been started and the modem's CID functions are active, they sit and wait for a call to occur.
When a call does come in, the modem will intercept the incoming CID data and send it to the Serial control. This causes the
DataAvailable event to fire. To read in the data, use the ReadAll method of the Serial control:
dim incomingtext as string
incomingtext = me.readall
incomingtext = replaceall(incomingtext,chr(10),"")
ParseIncoming(incomingtext)
ParseIncoming is a method that looks through the data and tries to find the appropriate CID information. It
performs many string manipulations based on the rules discussed earlier in the CID specification. Create the ParseIncoming method like so:
ParseIncoming(rawdata as string)
and add the following code:
dim i,msglength,messageposition as integer
dim msgtype,strippedmsg,temp as string
dim callername,callernum as string
messageposition=Instr(rawdata,"MESG = ")
if messageposition<>0 then
//we have caller id info!
msgtype=mid(rawdata,messageposition+7,1)
//which type of caller id transmission?
// for my test, it was the newer "MDMF" type
if msgtype=chr(128) then//"Ÿ" = $80 = 128
labeltype.text="MDMF"
else
labeltype.text="SDMF"
return
end if
//how long is the message?
msglength=asc(mid(rawdata,messageposition+8,1))
//display length of the entire CID msg
labellength.text=str(msglength)
//now we know the length, so we can
//retrieve the message from the string
strippedmsg=mid(rawdata,messageposition+9,msglength)
//parse the date information
temp=left(strippedmsg,10)
//display the date info
labeldate.text=ParseMyDate(temp)
//parse the name information
temp=mid(strippedmsg,11)
callername=ParseCallerName(temp)
//display the caller's name
labelname.text=callername
//parse the phone number information
temp=mid(strippedmsg,11+carryoverlength)
callernum=ParseCallerNumber(temp)
//display the phone number
labelphone.text=callernum
labelphone.refresh
end if
Note the following methods from the above code:
- ParseMyDate
- ParseCallerName
- ParseCallerNumber
These methods each take a string and parse specific information from it. Rather than list the code for each of
these methods for you here, you download the project and view them there.
Finally, to turn off the modem (and Caller ID feature), place this code in the Action event of StopButton:
serial1.write "AT#CID=0" + chr(13)
serial1.close
StartButton.enabled=true
me.enabled=false
What's Next?
That's it for this week. Again, you may download the completed code for this week's tutorial. Next week, we will look at
what happens when a caller hides the CID information from you. We'll also take a look at some fun tricks that you can use to
make your Caller ID application even more useful. See you then!
7-03-01
REALbasic News
by Erick Tejkowsi
Video Capture Plugin. Essence Software
has announced the availability of
VideoPlug 1.2. In this version:
- Carbon support for Mac OS X
- Control over compression, brightness, contrast, and audio gain
Build a Web Browser.
Alfred Van Hoek has released the latest Preview 2 version of
his HTMLrenderer/URLaccess plugin. This version lets
you download a file from the web and render it like a web browser.
Console your Games.
Noah Desch has updated his Game Console code
to version 1.2. GameConsole is a few classes
that let you create a console in your game similar to the QuakeIII console. This version has
over a dozen improvements, so don't miss it!
Parlez vous Francais?
Alsyd, a leading French Internet and scientific tool republisher,
has announced that it will localize and
distribute REALbasic 3.5.
New HTML Editor.
Nous_Enough has a new version of
the Made-with-REALbasic HTML editor
Attic PageImp.
Version 1.1 includes:
- Increased stability
- "Carbonized" to run natively on Mac OS 10.00 (X)
- Fresh new interface and icons
- Much improved stylesheet support
- 3 different automatic editing modes for HTML, text and stylesheets
- Better Tag Editor support
- Recognises and installs some PageSpinner menu extensions, and ButtonMaker
graphic plug-ins
- And more!
Interface problems?
Toby Rish has begun a site dedicated to creating great interfaces with REALbasic. If you'd like
to offer interface suggestions, please visit his site.
RadioBox Replacement.
George Clark has updated his RadioBox control.
New in this version:
- Built-in support for ContextualMenus
- Can now force a RadioBox to act with a MouseDown click rather than on MouseUp (useful for certain situations).
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