I use Debian 9 on a PC and a Samsung Z3 (Tizen operating system) phone. I was able, through a USB cable, to read the phone's memory card and write to it from Linux Mint, but the phone is not seen by Debian. I had hoped to put some music on it and a few photos.

[some hours later] I decided to make space for another partition on sda1 and put Xubuntu on it, which can communicate with the phone. However, I'd still like to know how to make it possible in Debian.

Where, and how have you looked?

Have you, in a root terminal ran the command 'lsusb'? If not, run the command, and post the output.

Have you, as root, looked at the output of dmesg? When you plug a device, it should show up in there, usually in the last 20 or so line of output. If you are not familiar with the output of dmesg, open a terminal and either use sudo dmesg, or su to root, and run dmesg. Do that before you plug the phone in. Plug the phone, and look again. You should see lines added for the new device.

Some phones, you need to go into the settings, and there may be a setting for allowing the phone to be a mass storage device. This is required so any linux system can see the storage on the phone.

Hope this helps.

Thank you. In other distributions SLP appears on the desktop when the phone is connected: but in Debian this does not happen although both lsusb and dmesg report the phone. The phone does not appear at the left of the screen either (in Thunar).

With the phone connected, run dmesg as root and check whether the output shows the phone; if so, how is it reported?

Note that dmesg commonly generates lots of output, so you may wish to pipe the output to a file so that you can examine the file in an editor at your leisure.

Thank you. Here is what dmesg says about the phone:

[ 486.620063] usb 1-4: new high-speed USB device number 2 using ehci-pci
[ 486.769291] usb 1-4: New USB device found, idVendor=04e8, idProduct=6860
[ 486.769298] usb 1-4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 486.769303] usb 1-4: Product: SLP
[ 486.769308] usb 1-4: Manufacturer: SAMSUNG
[ 486.769312] usb 1-4: SerialNumber: 0000c68b00006300

What desktop environment and file manager do you have on Debian? you'd think Debian would auto-mount. However can you mount the phone from the side-bar of the file manager?

XFCE and Thunar. The file manager does not show the phone.

This may have come about because Debian 9 does not provide "hal" or "usbmount".

This may not be relevant as I am running Ubuntu 16.04 and my phone is a Samsung Galaxy A5, but I had to install gvfs:-

# Install support for MTP protocol to link to Android.
sudo add-apt-repository ppa:langdalepl/gvfs-mtp
sudo apt-get update
sudo apt-get install gvfs
# Now restart.

Thank you. My phone runs Tizen, not Android. Nevertheless, there's no reason not to see if gvfs helps.