来电显示的实现
MODEM的AT命令CID和VCID是设置是不是来电显示的，如果电信开通了来电显示功能
就能通过MODEM来显示对方的电话号码。那么首先设置CID=1或是VCID=1
般来说来电显示的信息为：
DATE = MMDD "来电日期 MMDD
TIME = HHMM "来电时间 HHMM
NMBR = ######## "来电号码
程序实现如下,设置MSComm1的相关设置，并建两个Label为Label1和Label2
Function OpenCID(OpenCLose As Boolean) As Boolean
'打开或是关毕来电显示功能
On Error Resume Next
Dim ArrCID(1) As String
ArrCID(0) = "at#cid=" & IIf(openclode, 1, 0)
ArrCID(1) = "at#vcid=" & IIf(openclode, 1, 0)
MSComm1.RThreshold = 0
For i = 0 To 1
MSComm1.Output = ArrCID(i) & vbCr
EndTime = Timer + 0.5
Do While bStop = False
nTemp = nTemp + 1
If MSComm1.InBufferCount >= 2 Then
sTemp = MSComm1.Input
If InStr(sTemp, "OK") = 0 Then
bStop = True
OpenCID = True
Exit Function
End If
End If
If Timer >= EndTime Or ErrorCode Then Exit Do
Loop
Next i
OpenCID = False
MSComm1.RThreshold = 1
End Function
下面的函数显示来电号码并在窗体上的Label1的Label2上显示出来
Private Sub MSComm1_OnComm()
On Error Resume Next
Static Buffer As String
' 收到多于 RThreshold 属性设置的字符数（RThreshold 属性必须大于 0）。
'label1 = "收到" + Str(MSComm1.InBufferCount) + "个字符"
Buffer = Buffer + MSComm1.Input
Buffer = UCase(Buffer)
' Exit Sub
If InStr(1, Buffer, "RING", vbTextCompare) Then
'收到震铃
'Comm1.Output = "ATA" + Chr(13) '命令 Modem 摘机响应
Buffer = "" '清缓冲区字符
'mciExecute "sound " & SystemPath & "\ringin.wav"
Label1 = "状态：收到震铃"
Zhen = True
frmCallID.Show
frmCallID.ChangRing
ElseIf InStr(1, Buffer, "CONNECT", vbTextCompare) Then
'对方应答呼叫
Buffer = "" '清缓冲区字符
Label1 = "状态：已经建立连接"
ElseIf InStr(1, Buffer, "BUSY", vbTextCompare) Then
'对方线路忙
Buffer = "" '清缓冲区字符
Label1 = "状态：对方线路忙"
ElseIf InStr(1, Buffer, "No DIA", vbTextCompare) Then
Buffer = "" '清缓冲区字符
Label1 = "状态：拨出号码错,请检查电话线"
Command1_Click
ElseIf InStr(1, Buffer, "No CARRIER", vbTextCompare) Then
'对方未摘机或未响应
Buffer = "" '清缓冲区字符
Label1 = "状态：对方未摘机"
ElseIf InStr(1, Buffer, "NMBR =", vbTextCompare) Then
tmpStr = InStr(1, Buffer, "NMBR", vbTextCompare)
CallNum = Right(Buffer, Len(Buffer) - lll - 6)
Label2.Caption = "对方电话：" + CallNum
'Buffer = "" '清缓冲区字符
ElseIf InStr(1, Buffer, "OK", vbTextCompare) And Asc(Right(Buffer, 1)) = 10 Then
If Zhen = False Then Buffer = "" '清缓冲区字符
If Command1.Caption = "挂断" Then
Label2.Caption = "状态：已经播通电话：" + txtCallNum
End If
End If
End Sub