I am playing with a USR (us robotics) USB modem model 5637. in the past I used internal modems and had no issues. One this unit I plugged it in, dmesg says its recogized. I did "ln -s /dev/ttyACM0 /dev/ttyS4" this works. I then did "cu -l /dev/ttyS4" type "AT" and I get OK... looking good. When I "ATDT my number" I get a connection at 1200 baud (which I should) and funny characters... I thought looks like a parity thing. I then did "cu -e -l /dev/ttyS4" type "AT" and I get OK... Now when I do "ATDT my number" I get a connection at 1200 baud and I get readable characters. In the past internal PCI modems I never had to do anything special, just the cu -l /dev/ttyS4. I thought modem to modem handled all that speed/parity stuff and computer to modem just always worked given the correct baud rate. Does anyone know what the issue might be here. The reason I am asking is my program that talks to the modems (computer to modem) has always been setup for 8 data no parity and has always worked. When I use my program on the USB modem it is not working and I assumed from the parity issue above using "cu" to demonstrate. When I change my program to be 7 data bits and even parity it still did not work. Was wondering if anyone had any USB modem experience on centos and might know what is going on? Thanks, Jerry