Please include a detailed description as well as steps to reproduce the bug. User still can see modem dbus interface information after modem was removed from PC, also we didn't see the log of interface unregister and modem was removed. It will impact user to update their information of modem.
Please check whether this is a kernel/udev issue. oFono relies on udev to tell it when a device has been removed. A dmesg / udev monitor log might be useful here.
please see dmesg log: usb 1-3: new high speed USB device using ehci_hcd and address 18 usb 1-3: New USB device found, idVendor=12d1, idProduct=1404 usb 1-3: New USB device strings: Mfr=3, Product=2, SerialNumber=0 usb 1-3: Product: HUAWEI Mobile usb 1-3: Manufacturer: HUAWEI Technology usb 1-3: configuration #1 chosen from 1 choice option 1-3:1.0: GSM modem (1-port) converter detected usb 1-3: GSM modem (1-port) converter now attached to ttyUSB1 option 1-3:1.1: GSM modem (1-port) converter detected usb 1-3: GSM modem (1-port) converter now attached to ttyUSB2 option 1-3:1.2: GSM modem (1-port) converter detected usb 1-3: GSM modem (1-port) converter now attached to ttyUSB3 option 1-3:1.3: GSM modem (1-port) converter detected usb 1-3: GSM modem (1-port) converter now attached to ttyUSB4 option 1-3:1.4: GSM modem (1-port) converter detected usb 1-3: GSM modem (1-port) converter now attached to ttyUSB5 usb 1-3: USB disconnect, address 18 option: option_instat_callback: error -108 option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1 option 1-3:1.0: device disconnected option1 ttyUSB2: GSM modem (1-port) converter now disconnected from ttyUSB2 option 1-3:1.1: device disconnected option1 ttyUSB3: GSM modem (1-port) converter now disconnected from ttyUSB3 option 1-3:1.2: device disconnected option1 ttyUSB4: GSM modem (1-port) converter now disconnected from ttyUSB4 option 1-3:1.3: device disconnected option1 ttyUSB5: GSM modem (1-port) converter now disconnected from ttyUSB5 option 1-3:1.4: device disconnected