beginner needs help to create a serial port reader applicatino for a Mitel smdr

Hi guys I am creating a port reader that will simply capture the data that is received from a mitel smdr, I developed my port reader in c# using visual studio .NET 2005.

On the pc that I am doing development on, I have a Nortel smdr model that is attach to this computer via COM port, when I execute the program that I created it works by just simply capturing the data that is read into the serial port from the Nortel smdr model. Below is the code that I used.

__________code_______________________
this.sp = new SerialPort("COM1", 1200, Parity.None, 8, StopBits.One);
sp.Open();
string line = sp.ReadLine();
______________________________________________

But the program that I am developing is suppose to work with a mitel smdr model. However when I tried running the same program that I mentioned that I created previously, it did not read what was or should have been coming into the serial port, at the same time my port reader did open the port because when I tried to run hyper terminal I got an error saying that the port is already open. But even though it appears that the port is open I am not able to read the data that should be coming in

_______________QUESTION__________
1.) Is it possible that the way how I read the line in serial port as is shown in the code snippet above is wrong, which makes it only work for Nortel smdr and that mitel smdr requires different parameters??????????????? I am not really sure
2.) Does any one have any sample code snippets of how I should; read the data from the serial port properly
?????????????