This example ObexFS session is how I backup my old phone, a Siemens S45, connected with a plain serial cable to a serial port usb adapter.

$ mkdir /tmp/mnt

$ obexfs -t /dev/ttyUSB0 -- /tmp/mnt

$ rsync -av /tmp/mnt/ /tmp/phone-backup

building file list ... done
created directory /tmp/phone-backup
./
Address book/
Address book/5F02.adr
Address book/5F03.adr
Address book/7F02.adr
Address book/7F03.adr
Address book/9F02.adr
Address book/9F03.adr
Animation/
Animation/bomb.bmx
Animation/heart1.bmx
(another 50 lines...)

sent 10766 bytes  received 1106 bytes  1249.68 bytes/sec
total size is 7453  speedup is 0.63

$ fusermount -u /tmp/mnt

And similar ObexFS session with a Siemens S65, connected with a DCA-510/DCA-540 USB serial converter cable.

$ mkdir /tmp/mnt

$ obexfs -t /dev/ttyUSB0 -- /tmp/mnt

$ rsync -av /tmp/mnt/ /tmp/phone-backup

building file list ... done
created directory /tmp/phone-backup
./
Data/
Data/Animations/
Data/Animations/Blue abstract/
Data/Animations/Blue abstract/Blue_abstract_netsearch.gif
Data/Animations/Blue abstract/Blue_abstract_screensaver.gif
Data/Animations/Blue abstract/Blue_abstract_switch_off.gif
(another 470 lines...)

sent 4760618 bytes  received 8458 bytes  31479.05 bytes/sec
total size is 4733670  speedup is 0.99

$ fusermount -u /tmp/mnt