Using a Huawei E173 USB Modem for Calls (chan_dongle)

Connecting a Huawei E173 3G USB modem to MikoPBX via chan_dongle

The Huawei E173 is a USB 3G modem from Huawei that is compatible with the chan_dongle module for Asterisk. By using this modem with chan_dongle, you can configure Asterisk to make voice calls and send SMS messages over the GSM network, effectively turning the modem into a full-fledged GSM gateway.

Dongle modems can be unstable. They require reliable, stable power and a strong GSM signal.

Preparing the USB Modem

1. First, let’s see which USB devices are connected to the PC:

lsusb
Bus 001 Device 002: ID 12d1:1001 Huawei Technologies Co., Ltd. E169/E620/E800 HSDPA Modem
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 003: ID 0e0f:0002 VMware, Inc. Virtual USB Hub
Bus 002 Device 002: ID 0e0f:0003 VMware, Inc. Virtual Mouse
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

We’re interested in the device "12d1:1001 Huawei Technologies...".

• 12d1 – the vendor ID.

• 1001 – the product ID.

For the modem to function properly, you need to switch it to "1001" (modem-only mode).

1. Next, search for device info using the vendor ID "12d1":

dmesg | grep 12d1
[    2.828272] usb 1-1: New USB device found, idVendor=12d1, idProduct=1001, bcdDevice= 0.00

1. Then check for info by the USB device number "usb 1-1":

dmesg | grep 'usb 1-1'

[    2.262750] usb 1-1: new high-speed USB device number 2 using ehci-pci
[    2.828272] usb 1-1: New USB device found, idVendor=12d1, idProduct=1001, bcdDevice= 0.00
[    2.828479] usb 1-1: New USB device strings: Mfr=3, Product=2, SerialNumber=0
[    2.828641] usb 1-1: Product: HUAWEI Mobile
[    2.828754] usb 1-1: Manufacturer: HUAWEI Technology
[    2.856994] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0
[    2.861194] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB1
[    2.864265] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB2

We see the modem’s serial devices: ttyUSB0, ttyUSB1, ttyUSB2.

If these devices appear, half the work is done. If they’re missing, the modem may be in a mode other than 1001. The product ID can vary with different firmware versions.

On some devices, modem-only mode may appear as "140c".

Checking the Modem Settings

minicom -D /dev/ttyUSB0

You’ll see something like:

Welcome to minicom 2.8

OPTIONS: I18n
Compiled on Apr 26 2021, 18:06:16.
Port /dev/ttyUSB0, 12:30:42

Press CTRL-A Z for help on special keys

You can now enter AT commands to manage and configure the modem.

Example Commands

• AT^CARDLOCK? – Checks SIM lock status and the remaining attempts to enter an unlock code. (The modem’s response: CARDLOCK: A,B,0. If A=2, modem is unlocked; A=1, locked — SimLock; A=3, you either used all 10 attempts or have a customized firmware. B is the remaining number of attempts, typically 10.)

• AT^CARDLOCK="NCK Code" – Unlock the modem to work with all mobile operators (if you have the code).

• AT^CVOICE=? – Checks the modem’s voice support state (0 means voice is enabled).

• AT^CVOICE=0 – Enables voice functions on the modem.

• AT^U2DIAG=0 – Switch the modem into modem-only mode.

What to Verify?

1. Confirm the modem supports voice functions.

2. The modem must be in "modem-only" mode (ID 1001).

3. If possible (and if you have a code), unlock the modem for use with any operator.

chan_dongle for Asterisk

1. In the MikoPBX web interface, go to System → Customize System Files.

2. Open /etc/asterisk/modules.conf.

3. Set the mode to "Append to the end of the file".

4. Add:

load => chan_dongle.so

1. Open /etc/asterisk/dongle.conf for editing.

2. Choose "Replace Completely".

3. Paste the following configuration:

[general]
interval=15

[defaults]
context=public-direct-dial
group=0
rxgain=0
txgain=0
autodeletesms=yes
resetdongle=yes
u2diag=-1
usecallingpres=yes
callingpres=allowed_passed_screen
disablesms=no

language=en
smsaspdu=yes
mindtmfgap=45
mindtmfduration=80
mindtmfinterval=200

callwaiting=auto
disable=no
initstate=start
dtmf=relax

[dongle0]
audio=/dev/ttyUSB1
data=/dev/ttyUSB2

1. Re-open /etc/asterisk/modules.conf.

2. Again choose "Append to the end of the file".

3. Add contexts for SMS and USSD handling:

[dongle-incoming-ussd]
exten => ussd,1,Noop(Incoming USSD: ${BASE64DECODE(${USSDBASE64})})
exten => ussd,n,Hangup()

[dongle-incoming-sms]
exten => sms,1,Noop(Incoming SMS from ${CALLERID(num)} ${BASE64_DECODE(${SMS_BASE64})})
exten => sms,n,Hangup()

1. After configuring dongle.conf, you must restart your PBX.

Helpful resources:

• See the dongle.conf file for a description of configuration and options.
• More details in chan_dongle documentation.

• dongle0 is an arbitrary name of the line. It will be used in the Dial command for outgoing calls.

• audio and data are the TTY device paths discovered in the previous step. You may need to swap them if there’s no audio.

Configuring DID

Each dongle requires a DID number for correct inbound call handling.

1. Enter the Asterisk console:

asterisk -r

1. List the dongle devices:

mikopbx*CLI> dongle show devices
ID      Group State RSSI Model Firmware         IMEI IMSI Number
dongle0 0     Free  12   E173  11.126.15.00.209 ***  ***  79255283744

1. If the Number column is empty, run:

dongle cmd dongle0 AT+CPBS="ON"
dongle cmd dongle0 AT+CPBW=1,"79255283744",145

Replace dongle0 with your line’s identifier, and "79255283744" with the SIM’s phone number.

Restart your PBX afterwards.

Configuring an Inbound Route

1. In the web interface, go to Call Routing → Incoming Routing.

"Incoming routing" section

1. Create a new rule. In the DID field, specify the SIM’s phone number you set earlier:

DID Number field

Configuring Outbound Routes

1. In Call Routing → Providers, create a new SIP account with:

   • Name – “Dongle0” (or any name)

   • Host or IP – 127.0.0.1

   • Account Type – “Authentication by IP address, no password”

Provider Parameters

1. Copy the Provider ID from the browser address bar (e.g., SIP-TRUNK-C4153448).

Provider ID

1. In Call Routing → Outbound Routing, create a new rule for sending calls via the modem:

Outbound route

1. Go to System → System file customization and open /etc/asterisk/extensions.conf. Choose “Add to end of file” and add:

[SIP-TRUNK-C4153448-outgoing-custom]
exten => _[0-9*#+]!,1,Set(DIAL_COMMAND=Dongle/dongle0/${number})
 same => n,return

Replace SIP-TRUNK-C4153448 and dongle0 with your IDs.

Code for the file "extensions.conf"