Operating system name and version: Linus Debian Squeeze
Version of smsd: 3.1.14
Smsd installed from: sources
Name and model of a modem / phone: modem P300U
Interface: Cygnal Integrated USB to UART

I can't recognize this as a modem under linux. I configured with the option check_memory = 5 like said in instructions but nothing. Anyone whi had this problem please help me

No minicom, no nothing

I do not understand the question .

You could set loglevel = 7 in the smsd.conf, and restart smsd. Then show piece of a log, starting from the line "smsd: Smsd v3.1.14 started.".

Also show the content of smsd.conf.

Ok, welll actually wht says in the log is protocol error, the program sends an AT command to the modem and this doesn't retunr the expected OK

So obviously my problem is that Linux is not recognizing my modem (P300U) based on SIM600 as a modem. I found that with this program I could succeed in connecting my modem but I CAN'T and it's necessary for me, please if someone knows a way of making this P300U modem work under Linux Debian, please let me know.

Thanks in advance.

As dmesg shows "cp210x ttyUSB0: cp210x_open - Unable to enable UART", put that message to Google search. The first result is Fixing the cp210x open - Unable to enable UART Error - 04/17/2011. That page says that "The error is caused by the cp210x driver timing out too quickly". You need to modify the Linux source code, as instructed.

If the modification does not help, or you get another errors, just continue using some another modem.