I have an external powered USB hub and I'm using gammu to send some SMSs, but every time the daemon connect to one specific modem, it has the port changed. Gammu is able to send just one SMS and after that the port is changed. I've already tried using: /dev/ttyUSB3 /dev/serial/by-path/pci-0000:00:0b.0-usb-0:3.4.3:1.0-port0 There is anything to do which will stop the ports to be changed or use any other fixed port? Thanks.