GSM VoIP Gateway with Chan_dongle

A highly affordable GSM VoIP gateway can be obtained using Huawei E155X or compatible USB modems and chan_dongle, providing both inbound and outbound calls on GSM/3G networks.

Hardware requirements

Chan_dongle is able to work with many different USB modems from Huawei, such as K3715, E169 / K3520, E155X, E175X, K3765 and others. Read the full compatibility list here.
Before connecting the modem to your RPi, be sure to use a power supply rated at least 1A, better 1.2A or more. If your power supply does not provide enough current to power both the RPi and the modem, you can get problems booting the RPi, or calls to/from the GSM network fail with error “dongle disconnected”.
Alternatively a powered USB hub can be used as well. If you want to use 2 modems, an additional WiFi connection or other devices that require considerable amount of current, a powered USB hub is absolutely required.
In case you are using one of the older 256MB models with F1 and F2 still in place, you might want to consider bridging over F1 and F2, read more details here. This is however not required on the newer 512MB models, or when using a powered USB hub.

Not all Huawei USB modems work out of the box, on some of them voice calling capability has to be enabled first, some need to be upgraded with the latest firmware. Details on this can be found on the original chan_dongle wiki.
Before inserting the SIM into your modem please deactivate the PIN on your card. This can be done with any phone. Insert the SIM into your phone, deactivate PIN and you’re done. You can also use the Mobile Partner software – which comes with the modem itself – on a Windows computer to do this.

Setup and configuration

Once your modem has PIN deactivated, latest firmware and voice enabled, run this command:


This installer script installs, and creates an initial configuration. The script is provided with upgrade #11 (and improved further with upgrade #12). Once the installer has finished, connect your modem to the RPi. If it was connected already before, unplug it now and plug it in again. Some older modems still require usb_modeswitch to enable data/audio mode, for those a complete reboot of the RPi is recommended at this point.

Then log into FreePBX, in Connectivity – Trunks click Add Custom Trunk. Provide a trunk name, set Outbound CallerID to the number of your SIM, and enter in the field Custom Dial String:


Add an outbound route to use this trunk, as well as an incoming route. On the incoming route set DID Number to your SIM number, precisely matching the number you entered when running the install-dongle script.

More details on how to setup inbound and outbound routes can be found in the forum.

Sending and receiving SMS

The install-dongle script provides a few basic options to send and receive SMS. Received messages can be forwarded by email. If no email address is specified, messages are stored in /var/log/asterisk/sms.txt instead.
Additionally, received messages can optionally be forwarded to a mobile phone number on top of sending them by email. This is done through the first dongle0, your mobile operator’s charges apply for sending SMS.
In order to send out custom messages, a password protected web page can be activated during the install-dongle run. This page is located at http://raspbx/sms or http://raspbx.local/sms (for Mac).
A web page for sending USSDs is optionally available. Install it with:

apt-get install ussd-webpage

The page can be found at http://raspbx/ussd or http://raspbx.local/ussd (for Mac).


If it doesn’t work at this point, at first check if the interfaces of your modem match the configuration:

ls -l /dev/tty*

2 devices, ttyUSB1 and ttyUSB2 should show up. If the numbers are different, something like ttyUSB0 and ttyUSB1, edit /etc/asterisk/dongle.conf and change the values below [dongle0] accordingly.
Many modems require the usb_modeswitch program to switch over from CD-drive mode (for installing Windows drivers) to modem mode. The /dev/ttyUSB devices will not appear before the switch-over was done. Make sure to have all the latest upgrades on recent Debian Jessie based images to fix some initial bugs with usb_modeswitch. If your modem is still not switching it might be necessary to add a custom rule for usb_modeswitch.

Some users have reported voice calling with a specific mobile operator was not working, while using a sim card from a different provider with the same modem and RPi worked perfectly fine.

Troubleshooting power problems
In case the modem devices ttyUSB1 and ttyUSB2 are disappearing as soon as a call is set up (or also at other times), and later they appear again, it is most likely the modem is not sufficiently powered and thus disconnects again and again. Try these options:

  • Remove any USB extension cord from the modem and connect it directly.
  • In case a powered USB hub is used, try a different one or even try without it. With some of those hubs the modems just don’t work properly, although the current rating of the hub’s power supply is high enough.
  • If the modem is directly connected to the RPi (without a hub), the power supply has to power them both. Try different power supplies, as some have problems to keep their output voltage stable under higher load.
  • As a last resort, you can also try to use a different modem.

For more information, read the complete documentation here:

Modems reported working/not working

On top of the compatibility list on the original chan_dongle wiki, users of RasPBX have reported several modems to work fine with the RPi:

  • E153
  • E1550
  • E1552
  • E156G
  • E160
  • EG162
  • E166
  • E169
  • E171
  • E173 (some types of E173 seem to not work, only E173 with Qualcomm chipsets do work)
  • E1750
  • E180
  • E303
  • K3520 (not to confuse with K3520-z)
  • K3715
  • K3765a

The following modems had issues and could not me made working so far. Please let us know if they work for you nonetheless:

  • E150
  • E1752
  • E303C
  • E352
  • K3520-z

236 thoughts on “GSM VoIP Gateway with Chan_dongle

  1. Pingback: Raspberry Pi… Few sizes but fits many applications | Virtualised Fruit

  2. Guys,
    Probably someone can help with any advice on the issue. Asterisk throws ‘Dongle needs to be reinitialized. The SIM card is not ready yet’ message for one of my sim cards. I have three e171 dongles, two of them work perfectly. I tried to swap sim cards and ascertained that the problem is sim-related. After poking around with chan_dongle code I received evidence that the problem has something to do with AT+CNUM command, being used by chan_dongle module upon initializing phase. I pinged the dongle with that sim card with socat tool and got the following responses:

    +CPBS: “ON”,1,5




    That makes me to believe that every time chan_dongle attempts to initialize the dongle it palls it with CMD_AT_CNUM command and fails while getting ERROR response.
    The own number (MSISDN) of the sim card seems impossible to be changed using AT commands not directly while incerted into a cell phone (it can only be read by device). AT+CPBS=”ON” and AT+CPBW=,”+XXXXXXXXXXX”,128,”Voice” gave me just ERROR
    I have got stuck…. Replaced the sim card but still no joy (the same story)– it doesn’t seem to be provided by my mobile operator. Is that query important or can be commented out in a source code and re-compiled for running Asterisk inside Raspbx distro?

  3. Would it be possible to still have the RPi use 3G data (to access the Internet) from the modem after setting up asterisk and chan_dongle to handle voice/text?

    • No,of course you can’t.
      But it is possible if you have two dongles,and config one of them to be a 3G modem

  4. I found out that many dongles listed on github webpage
    “List of Supported Models” does NOT support voice feature!
    Such as huawei E153, the EU version is voice feature enabled,but China Unicom version is disabled.

    And also, you do NOT have to pay for dc-unlocker!
    There is a free software in russia called E1550_Russia_MTS_PatchDataCard1.0.0.3.
    This can do the same thing, almost all types of huawei dongle can be unlocked and voice enabled !
    There is a simple way to determine whether the voice feature is enabled or not.Just plug the dongle to a computer(even a 5V adapter),wait for 1min,
    use another phone to call the number of the simcard in the dongle.If it says”busy”,then it’s voice disabled, if “power off” you should just wait,it haven’t connected to the cell tower,if it rings, congratulations,your dongle is voice enabled.

  5. Bit too much trouble. VoIP to GSM gateway functionality is available by default on AVM Fritz!box 7360 and 7930 routers. It can also be installed on earlier models using the Freetz custom firmware (supports installing asterisk too). Cost ranges from 80 euro’s for new to 25 for a used one.

    Supports only one dongle each but multiple fritz!boxes can be connected to a single asterisk box.

  6. Hello!

    Iam kinda new to rasPBX. I went and setup the dongles for calls, sms, USSD.

    SMSs are having some issues, where USSD doesn’t go at all. I have that. Got USSD type 2 ‘USSD Terminated by network’ I am using E1553.

    It works on a full linux system, when tweak the at_reponse.c with a patch I found on google-code. Since This build is pre-build I can’t do much.

    Please, Help. I have 3 days on it (Build, reBuild, BackUp, restore). I think it might be 7bit character issue.

    dongle ussd dongle0 *xxx#
    [dongle0] USSD queued for send with id 0xb66404a8
    — [dongle0] Successfully sent USSD 0xb66404a8
    [2016-08-10 22:51:19] NOTICE[6339]: at_response.c:267 at_response_ok: [dongle0] Successfully sent USSD 0xb66404a8
    [dongle0] Got USSD type 2 ‘USSD Terminated by network’: ”
    [2016-08-10 22:51:21] WARNING[6396][C-00000001]: func_base64.c:81 base64_helper: Syntax: BASE64_DECODE() – missing argument!
    — Executing [ussd@dongle-incoming:1] NoOp(“Local/ussd@dongle-incoming-00000001;1”, “Incoming USSD: “) in new stack
    [2016-08-10 22:51:21] WARNING[6396][C-00000001]: func_base64.c:81 base64_helper: Syntax: BASE64_DECODE() – missing argument!
    — Executing [ussd@dongle-incoming:2] System(“Local/ussd@dongle-incoming-00000001;1”, “echo ‘2016-08-10 22:51:21 – dongle0: ‘ >> /var/log/asterisk/ussd.txt”) in new stack
    — Executing [ussd@dongle-incoming:3] Hangup(“Local/ussd@dongle-incoming-00000001;1”, “”) in new stack
    == Spawn extension (dongle-incoming, ussd, 3) exited non-zero on ‘Local/ussd@dongle-incoming-00000001;1’

  7. Pingback: Asterisk Gsm Huawei E173 | BBC Tips

  8. Pingback: Asterisk Modem Huawei | BBC Tips

  9. Ok with one dongle. My problem is with 2 dongle. I see them with ls /dev/ttyUSB*, I have USB0 USB1 USB2 USB3 USB4 USB5 but I see have one operative with asterisk –r // dongle show devices. I suppose that minicom work with one dongle only. Some people can help me? Thanks

    • If on linux, use imei/imsi to identify the dongles; you can add as many you want like this:
      ;exten=_tel_number_ ; optional

      ;exten=_tel_number_ ; optional

      Or the ttyUSB notation, usually like this:


  10. I just wonder if new chan_dongle for Asterisk 13 is going to be presented ever? It is available already for downloads from GitHub, so it looks as if it is the only one thing which keeps us on hold from Asterisk 13.

    • Asterisk 13 is already available for quite some time, please have a look at the FAQ. I plan to ship the next image with Asterisk 13 by default, but a few things still need to be sorted out.

  11. Dear all,
    I hope someone might drop me a hint as I ran out of guesses 🙁
    I have a modem E1550 which operates fine using AT commands, the modem is initialised correctly:
    raspbx*CLI> dongle show devices
    ID Group State RSSI Mode Submode Provider Name Model Firmware IMEI IMSI Number
    dongle0 0 Free 15 0 0 3 UK E1550 11.608.14.11.174 IMEI IMSI Number
    dongle.conf is also here :
    root@raspbx:/etc/asterisk# cat /etc/asterisk/dongle.conf
    interval=15 ; Number of seconds between trying to connect to devices
    ;—————————— JITTER BUFFER CONFIGURATION ————————–
    ;jbenable = yes ; Enables the use of a jitterbuffer on the receiving side of a
    ; Dongle channel. Defaults to “no”. An enabled jitterbuffer will
    ; be used only if the sending side can create and the receiving
    ; side can not accept jitter. The Dongle channel can’t accept jitter,
    ; thus an enabled jitterbuffer on the receive Dongle side will always
    ; be used if the sending side can create jitter.
    ;jbforce = no ; Forces the use of a jitterbuffer on the receive side of a Dongle
    ; channel. Defaults to “no”.
    ;jbmaxsize = 200 ; Max length of the jitterbuffer in milliseconds.
    ;jbresyncthreshold = 1000 ; Jump in the frame timestamps over which the jitterbuffer is
    ; resynchronized. Useful to improve the quality of the voice, with
    ; big jumps in/broken timestamps, usually sent from exotic devices
    ; and programs. Defaults to 1000.
    ;jbimpl = fixed ; Jitterbuffer implementation, used on the receiving side of a Dongle
    ; channel. Two implementations are currently available – “fixed”
    ; (with size always equals to jbmaxsize) and “adaptive” (with
    ; variable size, actually the new jb of IAX2). Defaults to fixed.
    ;jbtargetextra = 40 ; This option only affects the jb when ‘jbimpl = adaptive’ is set.
    ; The option represents the number of milliseconds by which the new jitter buffer
    ; will pad its size. the default is 40, so without modification, the new
    ; jitter buffer will set its size to the jitter value plus 40 milliseconds.
    ; increasing this value may help if your network normally has low jitter,
    ; but occasionally has spikes.
    ;jblog = no ; Enables jitterbuffer frame logging. Defaults to “no”.
    ; now you can set here any not required device settings as template
    ; sure you can overwrite in any [device] section this default values
    context=from-trunk-dongle ; context for incoming calls
    group=0 ; calling group
    rxgain=0 ; increase the incoming volume; may be negative
    txgain=0 ; increase the outgoint volume; may be negative
    autodeletesms=yes ; auto delete incoming sms
    resetdongle=no ; reset dongle during initialization with ATZ command
    ;u2diag=-1 ; set ^U2DIAG parameter on device (0 = disable everything except modem function) ; -1 not use ^U2DIAG command
    usecallingpres=yes ; use the caller ID presentation or not
    callingpres=allowed_passed_screen ; set caller ID presentation by default use default network settings
    disablesms=no ; disable of SMS reading from device when received
    ; chan_dongle has currently a bug with SMS reception. When a SMS gets in during a
    ; call chan_dongle might crash. Enable this option to disable sms reception.
    ; default = no
    language=en ; set channel default language
    smsaspdu=yes ; if ‘yes’ send SMS in PDU mode, feature implementation incomplete and we strongly recommend say ‘yes’
    mindtmfgap=45 ; minimal interval from end of previews DTMF from begining of next in ms
    mindtmfduration=80 ; minimal DTMF tone duration in ms
    mindtmfinterval=200 ; minimal interval between ends of DTMF of same digits in ms
    callwaiting=auto ; if ‘yes’ allow incoming calls waiting; by default use network settings
    ; if ‘no’ waiting calls just ignored
    disable=no ; OBSOLETED by initstate: if ‘yes’ no load this device and just ignore this section
    initstate=start ; specified initial state of device, must be one of ‘stop’ ‘start’ ‘remote’
    ; ‘remove’ same as ‘disable=yes’
    ;exten=+1234567890 ; exten for start incoming calls, only in case of Subscriber Number not available!, also set to CALLERID(ndid)
    dtmf=relax ; control of incoming DTMF detection, possible values:
    ; off – off DTMF tones detection, voice data passed to asterisk unaltered
    ; use this value for gateways or if not use DTMF for AVR or inside dialplan
    ; inband – do DTMF tones detection
    ; relax – like inband but with relaxdtmf option
    ; default is ‘relax’ by compatibility reason
    ; dongle required settings
    audio=/dev/ttyUSB1 ; tty port for audio connection; no default value
    data=/dev/ttyUSB0 ; tty port for AT commands; no default value
    The problem is that I do not get any calls… i can’t see anything in console.

    • If on linux, use imei/imsi to identify the dongles:


  12. Pingback: Asterisk for Raspberry Pi – My Technology | Republic

  13. Would Huawei E303F work? I am trying to avail a model from the list which is available on chan_dongle ‘s website but unfortunately those devices are not available.
    I am a newbi trying to make a RaspberryPi – GSM VOIP Gateway
    please help and oblige

      • I want to use a softphone with a SIP account to receive and make call, could you please tel as how to do ? I installled the last version of Asterisk and dongle on Raspberry 3 with unlocked and voice enabled E160X.
        thanks in advance for your help,

  14. Recently I moved to ‘Raspberry PI 2’ from ‘Raspberry PI A’. With RPI 2 I’m facing a problem in GSM call with chan_dongle, I can hear(on my soft VOIP) properly GSM voice, but the person on GSM side could not hear my voice properly(It is like voice modulation changed, high bass effect).

    I tried different codecs but no luck.

    I searched in many forums and only difference I can find-out on these two modules, big.LITTLE architecture used in RPI 2 CPU(

    Any one facing this issue? Any solution?

  15. Hello chan_dongle…can my post seeking help re chan_dongle compatability of the ZTE mf626 3g modem please be reposted? It was there for a day or two now its not there? I am hoping someone can read it and respond! I posted it after Ricardo’s post of Oct 27th!

  16. Am seeking advice on whether its worthwhile spending any more time getting a ZTE modem working on chan_dongle. I’ve voice enabled a ZTE mf626 usb drive, and made an outbound call via a windows PC …but when plugged into my rasPBX the error message includes:
    “…timedout while waiting ‘OK’ in response to ‘AT’…’
    I have inactivated the flash drive with the AT+ZCDRUN=8 command and as asked, wonder if its worth spending any more time on this eg via playing around with usb_modeswitch (of which the ‘rules’ file does not have an entry for the mf626)? Thanks.

    • There are many different compatible Huawei modems available and they are very cheap. So I’d rather get one of those than wasting time with a modem that does not work.

  17. Hi, just trying setting up dongle with a vodafone K3760. I did install-dongle, followed all the procedure, but I’m stuck with USB recognize. On Dmesg I get

    [ 787.662988] usb 1-1.2.2: new full-speed USB device number 10 using dwc_otg
    [ 787.797506] usb 1-1.2.2: not running at top speed; connect to a high speed hub
    [ 787.842889] usb 1-1.2.2: New USB device found, idVendor=0af0, idProduct=7501
    [ 787.875645] usb 1-1.2.2: New USB device strings: Mfr=2, Product=1, SerialNumber=0
    [ 787.908484] usb 1-1.2.2: Product: Option Configuration
    [ 787.938188] usb 1-1.2.2: Manufacturer: Option N.V.
    [ 787.976622] usb-storage 1-1.2.2:1.0: USB Mass Storage device detected
    [ 788.014272] usb-storage 1-1.2.2:1.1: USB Mass Storage device detected
    [ 788.050847] usb-storage 1-1.2.2:1.2: USB Mass Storage device detected
    [ 788.089632] usb-storage 1-1.2.2:1.3: USB Mass Storage device detected
    [ 788.127499] usb-storage 1-1.2.2:1.4: USB Mass Storage device detected
    [ 788.165173] usb-storage 1-1.2.2:1.5: USB Mass Storage device detected
    [ 788.194784] scsi host14: usb-storage 1-1.2.2:1.5
    [ 789.226962] scsi 14:0:0:0: Direct-Access SD HSUPA Modem PQ: 0 ANSI: 2
    [ 789.259735] sd 14:0:0:0: Attached scsi generic sg4 type 0
    [ 789.300183] sd 14:0:0:0: [sde] Attached SCSI removable disk

    But on ls -l /dev/tty* I can’t get ttyUSB 1 and 2

    crw-rw-rw- 1 root tty 5, 0 Jan 1 1970 /dev/tty
    crw–w—- 1 root tty 4, 0 Jan 1 1970 /dev/tty0
    crw——- 1 root tty 4, 1 Oct 27 15:00 /dev/tty1
    crw–w—- 1 root tty 4, 10 Jan 1 1970 /dev/tty10
    crw–w—- 1 root tty 4, 11 Jan 1 1970 /dev/tty11
    crw–w—- 1 root tty 4, 12 Jan 1 1970 /dev/tty12
    crw–w—- 1 root tty 4, 13 Jan 1 1970 /dev/tty13
    crw–w—- 1 root tty 4, 14 Jan 1 1970 /dev/tty14
    crw–w—- 1 root tty 4, 15 Jan 1 1970 /dev/tty15
    crw–w—- 1 root tty 4, 16 Jan 1 1970 /dev/tty16
    crw–w—- 1 root tty 4, 17 Jan 1 1970 /dev/tty17
    crw–w—- 1 root tty 4, 18 Jan 1 1970 /dev/tty18
    crw–w—- 1 root tty 4, 19 Jan 1 1970 /dev/tty19
    crw–w—- 1 root tty 4, 2 Jan 1 1970 /dev/tty2
    crw–w—- 1 root tty 4, 20 Jan 1 1970 /dev/tty20
    crw–w—- 1 root tty 4, 21 Jan 1 1970 /dev/tty21
    crw–w—- 1 root tty 4, 22 Jan 1 1970 /dev/tty22
    crw–w—- 1 root tty 4, 23 Jan 1 1970 /dev/tty23
    crw–w—- 1 root tty 4, 24 Jan 1 1970 /dev/tty24
    crw–w—- 1 root tty 4, 25 Jan 1 1970 /dev/tty25
    crw–w—- 1 root tty 4, 26 Jan 1 1970 /dev/tty26
    crw–w—- 1 root tty 4, 27 Jan 1 1970 /dev/tty27
    crw–w—- 1 root tty 4, 28 Jan 1 1970 /dev/tty28
    crw–w—- 1 root tty 4, 29 Jan 1 1970 /dev/tty29
    crw–w—- 1 root tty 4, 3 Jan 1 1970 /dev/tty3
    crw–w—- 1 root tty 4, 30 Jan 1 1970 /dev/tty30
    crw–w—- 1 root tty 4, 31 Jan 1 1970 /dev/tty31
    crw–w—- 1 root tty 4, 32 Jan 1 1970 /dev/tty32
    crw–w—- 1 root tty 4, 33 Jan 1 1970 /dev/tty33
    crw–w—- 1 root tty 4, 34 Jan 1 1970 /dev/tty34
    crw–w—- 1 root tty 4, 35 Jan 1 1970 /dev/tty35
    crw–w—- 1 root tty 4, 36 Jan 1 1970 /dev/tty36
    crw–w—- 1 root tty 4, 37 Jan 1 1970 /dev/tty37
    crw–w—- 1 root tty 4, 38 Jan 1 1970 /dev/tty38
    crw–w—- 1 root tty 4, 39 Jan 1 1970 /dev/tty39
    crw–w—- 1 root tty 4, 4 Jan 1 1970 /dev/tty4
    crw–w—- 1 root tty 4, 40 Jan 1 1970 /dev/tty40
    crw–w—- 1 root tty 4, 41 Jan 1 1970 /dev/tty41
    crw–w—- 1 root tty 4, 42 Jan 1 1970 /dev/tty42
    crw–w—- 1 root tty 4, 43 Jan 1 1970 /dev/tty43
    crw–w—- 1 root tty 4, 44 Jan 1 1970 /dev/tty44
    crw–w—- 1 root tty 4, 45 Jan 1 1970 /dev/tty45
    crw–w—- 1 root tty 4, 46 Jan 1 1970 /dev/tty46
    crw–w—- 1 root tty 4, 47 Jan 1 1970 /dev/tty47
    crw–w—- 1 root tty 4, 48 Jan 1 1970 /dev/tty48
    crw–w—- 1 root tty 4, 49 Jan 1 1970 /dev/tty49
    crw–w—- 1 root tty 4, 5 Jan 1 1970 /dev/tty5
    crw–w—- 1 root tty 4, 50 Jan 1 1970 /dev/tty50
    crw–w—- 1 root tty 4, 51 Jan 1 1970 /dev/tty51
    crw–w—- 1 root tty 4, 52 Jan 1 1970 /dev/tty52
    crw–w—- 1 root tty 4, 53 Jan 1 1970 /dev/tty53
    crw–w—- 1 root tty 4, 54 Jan 1 1970 /dev/tty54
    crw–w—- 1 root tty 4, 55 Jan 1 1970 /dev/tty55
    crw–w—- 1 root tty 4, 56 Jan 1 1970 /dev/tty56
    crw–w—- 1 root tty 4, 57 Jan 1 1970 /dev/tty57
    crw–w—- 1 root tty 4, 58 Jan 1 1970 /dev/tty58
    crw–w—- 1 root tty 4, 59 Jan 1 1970 /dev/tty59
    crw–w—- 1 root tty 4, 6 Jan 1 1970 /dev/tty6
    crw–w—- 1 root tty 4, 60 Jan 1 1970 /dev/tty60
    crw–w—- 1 root tty 4, 61 Jan 1 1970 /dev/tty61
    crw–w—- 1 root tty 4, 62 Jan 1 1970 /dev/tty62
    crw–w—- 1 root tty 4, 63 Jan 1 1970 /dev/tty63
    crw–w—- 1 root tty 4, 7 Jan 1 1970 /dev/tty7
    crw–w—- 1 root tty 4, 8 Jan 1 1970 /dev/tty8
    crwxrwxr-x 1 asterisk asterisk 4, 9 Oct 27 15:17 /dev/tty9
    crw–w—- 1 root tty 204, 64 Jan 1 1970 /dev/ttyAMA0
    crw-rw—- 1 root dialout 244, 0 Oct 27 15:02 /dev/ttyHS0
    crw-rw—- 1 root dialout 244, 1 Oct 27 15:02 /dev/ttyHS1
    crw-rw—- 1 root dialout 244, 2 Oct 27 15:02 /dev/ttyHS2
    crw-rw—- 1 root dialout 244, 3 Oct 27 15:02 /dev/ttyHS3
    crw——- 1 root root 5, 3 Jan 1 1970 /dev/ttyprintk

    I also tried modelswitch and as found into another forum, I did

    root@raspbx:~# /usr/sbin/usb_modeswitch –default-vendor 0x0af0 –default-product 0x7501 –message-endpoint 0x01 –message-content 55534243785634120100000080000601000000000000000000000000000000
    Look for default devices …
    product ID matched
    Found devices in default mode (1)
    Access device 010 on bus 001
    Current configuration number is 1
    Use interface number 0
    Use endpoints 0x01 (out) and 0x81 (in)
    Error: can’t use storage command in MessageContent with interface 0;
    interface class is 255, expected 8. Abort

    No luck and no way. Can you give me an advice?