• Using Yeaphone

For special use cases Yeaphone provides a few command-line options. In a multi-head environment you may choose a specific handset (out of multiple connected devices) using the option --id. With option -w or --wait the application can be instructed to wait for the device to be connected and to not terminate if the device gets disconnected.

    --id=<id>       Attach to the device with an ID <id>.
    --wait=[<sec>]  Check for the handset every <sec> seconds.
    -w              Check for the handset every 10 seconds.
    --help|-h       Print this help message.

• Linphone >= 1.7.1
• Yeaphone 0.1.5

For SlugOS/BE 4.8beta downloading the necessary files into the cross-compile environment could look like:

wget http://download.devbase.at/voip/linphone_2.1.1.bb

wget http://download.devbase.at/voip/yeaphone_0.1.5.bb cd ~/slugos-4.8-beta/@]

Note that this will only build the console version of linphone (as yeaphone's dependency). If you also want the GUI to be built you need to adjust the BitBake file linphone_2.1.1.bb.

Setting a SIP Server

The SIP servers for Yeaphone have to be configured through linphonec, the console version of Linphone. The following example shows how to get a working connection to a VoIP provider (user input printed bold).

Using linphonec the VoIP connection can be tested immediately before using Yeaphone. Commands still have to be entered through the terminal and the PC keyboard though. Note that if other sound cards are connected to the system, than it is likely that at this stage the speaker and microphone of the Yealink handset are not used yet. Yeaphone will later choose the correct audio settings automatically.

The most important commands of linphonec are:

Providing Yeaphone-Specific Parameters

Now the configuration file ~/.yeaphonerc has to be created manually. In order to correctly understand the phone number of incoming calls, Yeaphone needs the parameters intl-access-code, natl-access-code, and country-code according to your country.

    intl-access-code  00
    natl-access-code  0
    country-code      43

For the USA this would be:

    intl-access-code  011
    natl-access-code  1
    country-code      

In ~/.yeaphonerc you can also spedify custom ringtones for different numbers by adding lines according to the following example:

    ringtone_default   /usr/share/yeaphone/ringtones/default_p1k.bin
    ringtone_01234567  /usr/share/yeaphone/ringtones/special_p1k.bin
    ringtone_0555777   doorbell_p1k.bin

If you specify relative paths to the ringtones, they are based on $HOME/.yeaphone/ringtone.

Another feature to be configured in ~/.yeaphonerc is the minimum ring duration. If for a certain caller ID the duration of the ring should be at least 5 seconds, this can be specified as:

    minring_01234567  5

If in its idle state the handset should not only display the current date and time but also a certain fixed text, then the option display-id comes in handy. This makes sense especially in an environment where multiple handsets are operated next to each other and there is danger of confusing them. Example:

    display-id  "  --1234--"

Creating a rule for udev

As Yeaphone should not be run by the user <i>root</i> for security reasons, the access rights of the files providing the interface to the yealink driver have to be adjusted. The following line changes the group from root to voip assuming that the yeaphone user is a member of this group. The line has to be writting to a file called /etc/udev/rules.d/99-yealink.rules.

    KERNEL=="event*", DRIVERS=="yealink", GROUP="voip", RUN+="/bin/sh -c '/bin/chgrp voip /sys$env{PHYSDEVPATH}/*'"

To activate the rule on a running system, the handset has to be unplugged and plugged in again.

    <h2>Using Yeaphone</h2>

    <p>When invoking <i>yeaphone</i> the output on the console should
    look similar to this:</p>

Using Yeaphone

When invoking yeaphone the output on the console should look similar to this:

    user@NSLU2:~# <b>yeaphone</b>
    Ready
    Registration on sip:sipgate.at successful.

At the same time the current date and time are show on the handset's display, a quick sequence of status messages appear, and finally the lower part of the display should be empty (or show the text set with 'display-id'). Now the handset's keyboard can be used to place and receive calls.

• 0-9,*,#\\

• ▲ + <0-9>\\

• 0-9,*,#\\

• ▲ + <0-9>\\

The following performance measurements have been done using linphonec on a TurboSlug with an ARM5-optimized SPEEX library 1.2beta1 and SlugOS/4.8 (OABI):

The NSLU2 does not have enough horse power for echo cancellation or the SPEEX codecs, these should be turned off in the configuration file ~/.linphonerc.

The following article describes how to connect and use a YeaLink USB-P1K handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by the Linux kernel module yealink (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (cistrix, comsel, freshtel, laser, peoplefone, siptronic, us robotics, etc). Please note that nowadays most devices advertised as USB-P1K are actually its successor, the USB-P1KH. Although it is not supported by the driver shipped with the kernel, there is a new version of the yealink kernel module available at http://www.devbase.at/svn/view.cgi/yealink-module/?root=voip for kernel versions >= 2.6.18.

There is no support for models other than the USB-P1K(H) at this time, but some may not need much work in the application.

The following article describes how to connect and use a YeaLink USB-P1K handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by the Linux kernel module yealink (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (cistrix, comsel, freshtel, laser, peoplefone, siptronic, us robotics, etc). Please note that nowadays most devices advertised as USB-P1K? are actually its successor, the USB-P1KH?. Although it is not supported by the driver shipped with the kernel, there is a new version of the yealink kernel module available at http://www.devbase.at/svn/view.cgi/yealink-module/?root=voip for kernel versions >= 2.6.18.

There is no support for models other than the USB-P1KH at this time, but some may not need much work in the application.

• Linphone 1.6.0 + a patch for Linphone 1.6.0 (Note: Linphone >= 1.7.1 already includes all patches)

• only for linux kernels < 2.6.18: patched kernel module usbhid

The BitBake files are available in the OpenEmbedded database but can also be downloaded from the developer's web-site for Yeaphone: http://www.devbase.at/voip/yeaphone.php

For SlugOS/BE 3.10beta downloading the necessary files into the cross-compile environment could look like:

Alternatively there are compiled packages available for everything you will need to run Yeaphone at feed.devbase.at.

• for linux kernels < 2.6.18: patched kernel module usbhid

Currently the corresponding BitBake files as well as the usbhid-patch are not yet available in the official databases but can be downloaded from the developer's web-site for Yeaphone: http://www.devbase.at/voip/yeaphone.php

The following article describes how to connect and use a YeaLink USB-P1K handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by the Linux kernel module yealink (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (cistrix, comsel, freshtel, laser, peoplefone, siptronic, us robotics, etc). There is no support for models other than the USB-P1K at this time, but that's definitely a goal for future releases.

The following performance measurements have been done using linphonec on a TurboSlug with an ARM5-optimized SPEEX library 1.2beta1:

The following article describes how to connect and use a YeaLink USB-P1K handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by the Linux kernel module yealink (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (cistrix, comsel, freshtel, laser, peoplefone, siptronic, us robotics, etc). There is no support for models other than the USB-P1K? at this time, but that's definitely a goal for future releases.

• Performance Considerations

• Linphone 1.6.0
• a patch for Linphone 1.6.0

Currently the corresponding BitBake files are not yet available in the official databases but can be downloaded from the developer's web-site for Yeaphone: http://www.devbase.at/voip/yeaphone.php

For SlugOS/BE 3.10beta downloading the necessary files into the cross-compile environment would look like:

wget http://download.devbase.at/voip/linphone_1.6.0.bb

wget http://download.devbase.at/voip/yeaphone_0.1.bb cd ~/releases/slugos-3.10-beta/@]

Note that this will also compile linphone (as yeaphone's dependency) which by default builds both the console version and the GUI. If you do not want all the Gnome stuff to be built you need to adjust the BitBake file linphone_1.6.0.bb - comments "console-only version" inside this file will help you doing that.

Using linphonec the VoIP connection can be tested immediately before using Yeaphone. The speaker and microphone of the Yealink handset can be used already, commands still have to be entered through the terminal and the PC keyboard though. The most important commands of linphonec are:

To correctly understand the phone number of incoming calls, Yeaphone needs some adjustments in the file ~/.yeaphonerc. After terminating yeaphone the parameters intl-access-code, natl-access-code, and country-code should be changed to your countries access codes.

An example for Austria would be:

      intl-access-code 00
      natl-access-code 0
      country-code     43

For the USA this should be:

      intl-access-code 011
      natl-access-code 1
      country-code     1

Performance Considerations

The following performance measurements have been done using linphonec on a "Turbo-Slug" (266 MHz?) with an ARM5?-optimized SPEEX library 1.2beta1:

• Codecs PCMU, PCMA, GSM: There is no significant CPU load during the phone call.
• Echo Cancellation: With echo cancellation turned on the NSLU2 simply cannot keep up with the audio streams, only a fraction of the signal reaches the speaker.
• SPEEX (wide-band, 16kb): The CPU load is between 50 and 70 %, occasionally there are audible cuts. The memory consumption rises to 50 %!
• SPEEX (narrow-band, 8kb): The CPU load stays between 30 and 40 %, there are still some audible cuts.

Conclusion: The NSLU2 does not have enough horse power for echo cancellation or the SPEEX codecs, these should be turned off in the configuration file .linphonerc.

• Linphone 1.5.1
• a patch for Linphone 1.5.1

Copy/extract the downloaded files into your cross-compile environment. For SlugOS/BE 3.10beta this would be something like:

tar zxvf <path-to-download-dir>/linphone-1.5.1-bb.tgz

Note that this will also compile linphone (as yeaphone's dependency) which by default builds both the console version and the GUI. If you do not want all the Gnome stuff to be built you need to adjust the BitBake file linphone_1.5.1.bb - comments inside this file will help you doing that.

• Known Problems

Known Problems

There is a rather annoying memory leak, which increases memory usage by ~12KB with every reregistration. It occurs in both linphonec and yeaphone, so it is probably caused by one of the libraries used.

As a consequence please kill & restart yeaphone regularly, especially if you do not have swap space enabled!

The various phone keys have the following functions:

Table of contents

• Basic Architecture
• Installation
• Software Setup
• Usage

To correctly understand the phone number of incoming calls, Yeaphone needs some adjustments in the file ~/.yeaphonerc. After terminating yeaphone the parameters intl-access-code, natl-access-code, and country-code should be changed accordingly, the default values work for Austria only.

Usage

Start and stop the VoIP connection (corresponds to turning on/off a phone)

• 0-9\\

• C\\

• C pressed long
  Remove the complete number
• <red key>
  Remove the complete number
• <green key>
  Initiate the call
• # + <0-9>
  No number dialed yet: Recall and display a number from memory X
  Number already dialed: Store the currently displayed number at memory X

1. during a phone call
   • 0-9,*,#
     Generate DTMF tones
   • <red key>
     Terminate the call
   • VOL-/+ (on some models: IN/OUT)
     Adjust the speaker's volume
2. after a phone call (with the last number displayed)
   • 0-9
     Dial a new phone number
   • C
     Remove the complete number
   • <red key>
     Remove the complete number
   • <green key>
     Redial the last number
   • # + <0-9>
     Store the last number to memory X
3. when the phone rings
   • #
     Mute the ringing without picking up
   • <red key>
     Immediately terminate the call without picking up
   • <green key>
     Pick up
4. general
   • <red key> pressed long
     Start and stop the VoIP? connection (corresponds to turning on/off a phone)

Phone Keys

The various keys have the following functions:

1. before a phone call

          * C pressed long
            Remove the complete number
          * <red key>
            Remove the complete number
          * <green key>
            Initiate the call
          * # + <0-9>
            No number dialed yet: Recall and display a number from memory X
            Number already dialed: Store the currently displayed number at memory X 

2. during a phone call

          * 0-9,*,#
            Generate DTMF tones
          * <red key>
            Terminate the call
          * VOL+/-
            Adjust the speaker's volume 
   3. after a phone call (with the last number displayed)
          * 0-9
            Dial a new phone number
          * C
            Remove the complete number
          * <red key>
            Remove the complete number
          * <green key>
            Redial the last number
          * # + <0-9>
            Store the last number to memory X 
   4. when the phone rings
          * #
            Mute the ringing without picking up
          * <red key>
            Immediately terminate the call without picking up
          * <green key>
            Pick up 
   5. general
          * <red key> pressed long
            Start and stop the VoIP? connection (corresponds to turning on/off a phone) 

• help [<command>]\\

• call <phone number or SIP address>\\

• answer\\

• terminate\\

• quit
  unregisters at the VoIP provider and quits linphonec

Yeaphone has to be configured through linphonec, the console version of Linphone. The following example shows how to get a working connection to a VoIP provider (user input printed bold).

    root@NSLU2:~# linphonec
    Ready
    linphonec> soundcard list
    0: ALSA: default device
    1: ALSA: USB Audio
    2: ALSA: VOIP USB Phone
    3: OSS: /dev/dsp
    4: OSS: /dev/dsp1
    linphonec> soundcard use 2
    Using sound device ALSA: VOIP USB Phone
    linphonec> proxy add
    Adding new proxy setup. Hit ^D to abort.
    Enter proxy sip address: sip:sipgate.at
    Your identity for this proxy: sip:1234567@sipgate.at
    Do you want to register on this proxy (yes/no): yes
    Specify register expiration time in seconds (default is 600): 600
    Expiration: 600 seconds
    Specify route if needed: [leave empty]
    No route specified.
    --------------------------------------------
    sip address: sip:sipgate.at
    route:
    identity: sip:1234567@sipgate.at
    register: yes
    expires: 600
    --------------------------------------------
    Accept the above proxy configuration (yes/no) ?: yes
    Proxy added.
    linphonec>
    Password for 1234567 on "sipgate.at": [enter password]
    Registration on sip:sipgate.at sucessful.
    linphonec>

Using linphonec the VoIP connection can be tested immediately before using Yeaphone. The speaker and microphone of the Yealink handset can be used already, commands still have to be entered through the PC keyboard though. The most important commands of linphonec are:

• help [<command>]

shows the available commands and provides a detailed description for each command

• call <phone number or SIP address>

dials the specified phone number of SIP address

• answer

answers an incoming call

• terminate

terminates an (incoming or outgoing) call

• quit

unregisters at the VoIP? provider and quits linphonec

As soon as calls can be make this way, linphonec can be stopped and yeaphone can be invoked. Its output should look similar to this:

    root@NSLU2:~# yeaphone
    path_sysfs = /sys/bus/usb/drivers/yealink/3-1.3:1.3/
    path_buf = /dev/input/event2
    Ready
    Registration on sip:sipgate.at sucessful.

At the same time the current date and time are show on the handset's display, a quick sequence of status messages appear, and finally the lower part of the display should be empty. Now the handset's keyboard can be used to place and receive calls.

Yeaphone has to be configured through linphonec, the console version of Linphone. The following example shows how to get a working connection to a VoIP provider (user input printed bold).

 root@NSLU2:~# linphonec
 Ready
 linphonec> soundcard list
 0: ALSA: default device
 1: ALSA: USB Audio
 2: ALSA: VOIP USB Phone
 3: OSS: /dev/dsp
 4: OSS: /dev/dsp1
 linphonec> soundcard use 2
 Using sound device ALSA: VOIP USB Phone
 linphonec> proxy add
 Adding new proxy setup. Hit ^D to abort.
 Enter proxy sip address: sip:sipgate.at
 Your identity for this proxy: sip:1234567@sipgate.at
 Do you want to register on this proxy (yes/no): yes
 Specify register expiration time in seconds (default is 600): 600
 Expiration: 600 seconds
 Specify route if needed: [leave empty]
 No route specified.
 --------------------------------------------
 sip address: sip:sipgate.at
 route:
 identity: sip:1234567@sipgate.at
 register: yes
 expires: 600
 --------------------------------------------
 Accept the above proxy configuration (yes/no) ?: yes
 Proxy added.
 linphonec>
 Password for 1234567 on "sipgate.at": [enter password]
 Registration on sip:sipgate.at sucessful.
 linphonec>

[@root@NSLU2:~# linphonec

linphonec>@]

 [root@NSLU2:~# linphonec

linphonec>]

 ->root@NSLU2:~# linphonec
   Ready
   linphonec> soundcard list
   0: ALSA: default device

Yeaphone has to be configured through linphonec, the console version of Linphone. The following example shows how to get a working connection to a VoIP provider (user input printed bold).

root@NSLU2:~# ''linphonec''
Ready
linphonec> soundcard list
0: ALSA: default device
1: ALSA: USB Audio
2: ALSA: VOIP USB Phone
3: OSS: /dev/dsp
4: OSS: /dev/dsp1
linphonec> soundcard use 2
Using sound device ALSA: VOIP USB Phone
linphonec> proxy add
Adding new proxy setup. Hit ^D to abort.
Enter proxy sip address: sip:sipgate.at
Your identity for this proxy: sip:1234567@sipgate.at
Do you want to register on this proxy (yes/no): yes
Specify register expiration time in seconds (default is 600): 600
Expiration: 600 seconds
Specify route if needed: [leave empty]
No route specified.
--------------------------------------------
sip address: sip:sipgate.at
route:
identity: sip:1234567@sipgate.at
register: yes
expires: 600
--------------------------------------------
Accept the above proxy configuration (yes/no) ?: yes
Proxy added.
linphonec>
Password for 1234567 on "sipgate.at": [enter password]
Registration on sip:sipgate.at sucessful.
linphonec>

Alternatively and as long as Yeaphone is not part of the official ipkg feeds, there are compiled packages available for everything you will need to run Yeaphone at feed.devbase.at.

This gap is closed by Yeaphone, which interfaces to the kernel module and provides VoIP functionality by using the liblinphone SIP phone backend.

Alternatively and as long as Yeaphone is not part of the official ipkg feeds, there are compiled packages available for everything you will need to run Yeaphone at .

Software Setup

The following article describes how to connect and use a YeaLink USB-P1K handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by the Linux kernel module yealink (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (cistrix, comsel, freshtel, laser, peoplefone, siptronic, us robotics, etc).

This gap is closed by Yeaphone, which interfaces to the kernel module and provides VoIP functionality by using the liblinphone SIP phone backend. <!--The basic architecture is shown in the following diagram.

The following article describes how to connect and use a YeaLink USB-P1K handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by the Linux kernel module 'yealink' (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (cistrix, comsel, freshtel, laser, peoplefone, siptronic, us robotics, etc).

Copy/extract the downloaded files into your cross-compile environment. For OpenSlug 3.10beta this would be something like:

Note that this will also compile linphone (as yeaphone's dependency) which by default builds both the console version and the GUI. If you do not want all the Gnome stuff to be built you need to adjust the BitBake file linphone_1.4.1.bb - comments inside this file will help you doing that.

xy

As mentioned above the USB-P1K provides the basic phone interface (speaker, microphone, keys, display) but no VoIP functionality. On the other side there are the numerous VoIP soft phones, most of which can only be controlled via their GUI and therefore are not suitable for the NSLU2.

This gap is closed by Yeaphone, which interfaces to the kernel module and provides VoIP functionality by using the liblinphone SIP phone backend. The basic architecture is shown in the following diagram.

This gap is closed by YeaPhone?, which interfaces to the kernel module and provides VoIP? functionality by using the liblinphone SIP phone backend. The basic architecture is shown in the following diagram.

Yeaphone's main features are:

• Yeaphone 0.1

Currently the corresponding BitBake files are not available in the official databases and can only be downloaded from the developer's web-site of Yeaphone: http://www.devbase.at/voip/yeaphone.php

Then you can compile Yeaphone:

tar zxvf <path-to-download-dir>/linphone-1.4.1-bb.tgz mkdir ../yeaphone cd ../yeaphone cp <path-to-download-dir>/yeaphone_0.1.bb . cd ~/slugos-3.10-beta/@]

bb yeaphone

This gap is closed by YeaPhone?, which interfaces to the kernel module and provides VoIP? functionality by using the . The basic architecture is shown in the following diagram.

The following article describes how to connect and use a YeaLink USB-P1K handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by a Linux kernel module (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (cistrix, comsel, freshtel, laser, peoplefone, siptronic, us robotics, etc).

The following article describes how to connect and use a http://www.yealink.com/english/prodetail_p1k.htmYeaLink USB-P1K? handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by a Linux kernel module (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (cistrix, comsel, freshtel, laser, peoplefone, siptronic, us robotics, etc).

Installation

The necessary parts are

• Linphone 1.4.1
• a patch for Linphone 1.4.1
• YeaPhone 0.1

Currently the corresponding BitBake files are not available in the official databases and can only be downloaded from the developer's web-site of YeaPhone?: http://www.devbase.at/voip/yeaphone.php

Now copy the downloaded files into your cross-compile environment. For OpenSlug 3.10beta this would be something like:

cd ~/slugos-3.10-beta/openembedded/packages/linphone/
tar zxvf <path-to-download-dir>/linphone-1.4.1-bb.tgz
mkdir ../yeaphone
cd ../yeaphone
cp <path-to-download-dir>/yeaphone_0.1.bb .
cd ~/slugos-3.10-beta/

Now compile yeaphone: bb yeaphone

Note that this will also compile linphone (as yeaphone's dependency) which by default builds both the console version and the GUI. If you do not want all the Gnome stuff to be build you need to adjust the BitBake file linphone_1.4.1.bb - comments inside this file will help you doing that.

The following article describes how to connect and use a http://www.yealink.com/english/prodetail_p1k.htm? handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by a Linux kernel module (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (cistrix, comsel, freshtel, laser, peoplefone, siptronic, us robotics, etc).

• Installation

As mentioned above the USB-P1K provides the basic phone interface (speaker, microphone, keys, display) but no VoIP? functionality. On the other side there are the numerous VoIP soft phones, most of which can only be controlled via their GUI and therefore are not suitable for the NSLU2.

This gap is closed by YeaPhone?, which interfaces to the kernel module and provides VoIP? functionality by using the http://www.linphone.org/?. The basic architecture is shown in the following diagram. diagram to be added here...

YeaPhone's main features are:

• Display the phone number of incoming and outgoing calls
• Show the duration of a call
• Store and recall 10 phone numbers
• Mute the ring tone of incoming calls
• Adjustable volume of the speaker
• Send DTMF tones

[[#Installation] Installation

The following article describes how to connect and use a YeaLink USB-P1K handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K was chosen because it is well-supported by a Linux kernel module (see http://savannah.nongnu.org/projects/usbb2k-api/). It is sold for ~30€ under various brand names (peoplefone, laser, comsel, freshtel, etc).

Table of contents

• Basic Architecture

Basic Architecture

WORK IN PROGRESS....

There are various USB phones available which are marketed as VoIP phones. While usually rather cheap their built-in logic does not provide much more than an audio device, reading a user's key presses and possibly displaying simple messages.

The following article describes how to connect and use a YeaLink USB-P1K? handset with the NSLU2 as a standalone SIP VoIP phone. The USB-P1K? was chosen because it is well-supported by a Linux kernel module. It is sold for ~30€ under various brand names (peoplefone, laser, comsel, freshtel, etc).

There are various USB phones available which are marketed as VoIP? phones. While usually rather cheap their built-in logic does not provide much more than an audio device, reading a user's key presses and possibly displaying simple messages.

The following article describes how to connect and use a YeaLink? USB-P1K? handset with the NSLU2 as a standalone SIP VoIP? phone. The USB-P1K? was chosen because it is well-supported by a Linux kernel module. It is sold for ~30€ under various brand names (peoplefone, laser, comsel, freshtel, etc).