AT Commands For Vb.Net ASp.net To Send SMS Using GSM MODEM

[rahul2310]

Hi I am Developing web application in asp.net 4.0 (vb.NET)
I am using Sim900A GSM Modem to Send SMS using AT Command from VB.NET Below is my code but it does not work
whats wrong with the code

Dim ph_no As String
ph_no = Char.ConvertFromUtf32(34) + txtadphonenorec.Text + Char.ConvertFromUtf32(34)

SP.Write("AT")
SP.Write("AT+CMGF=1" & vbCrLf)
SP.Write("AT+CMGS=" & ph_no & "" & vbCrLf)
SP.Write(txtmsg.Text + Char.ConvertFromUtf32(26))
Response.Write("Send")

Please Help

[Luk3r]

What error are you getting? I would start by changing line 4 to this

SP.Write("AT" & vbCrLf)

[rahul2310]

i tried your way but still it doesn't work
I am not getting any error but message is not getting sent.
When i try AT commands from hyper terminal it works
Plz help

[Luk3r]

If no errors, then I'm going to assume that the phone number syntax is wrong. I would suggest trying something like this on line 6:

SP.Write("AT+CMGS=15554443333"& vbCrLf)

Where 1555444333 represents a 10 digit phone number (1-555-444-3333) and you should replace what I've written with the phone number you are trying to send a text message to.

[rahul2310]

I tried Your way but still it doesn't work Luk3r
From hyper terminal mobile number in double quotes works.
But not from the code

[rahul2310]

Does code changes if GSM modem is connected to USB Port