How to Successfully Tap Your (SIP) VOIP Phone Line for Free

Posted on May 4th, 2008 by Reiner.
Categories: English, Computers.

I’d like to present a free solution for Windows XP that reliably records incoming and outgoing SIP phone calls. I’m currently using it to record traditional conference calls for a team of software developers.

What you need

What you’ll get

  • A .wav file for each outgoing or incoming VOIP call.
  • There are additional components available from OrecX (some of which are being sold and thus are not for free), e.g. for saving phone calls within a database for later retrieval. I neither used nor needed those, as my primary concern was just to record daily stand-up telephone meetings.

How to Install

  • From Oreka: Download the files for your system environment
  • Install the Oreka audio capture server

Fine Tuning Capture Formats

By default, Oreka will produce .WAV-files using GSM compression. GSM is widely used for mobile phones, thus files are very small (about 100kBytes/minute), but sound quality is a little bit on the dull side and older applications might fail to understand GSM encoding. If space is of lesser concern, I’d recommend the plain old uncompressed pcmwav format (about 1MByte/minute) that can be read by virtually any program, or the ulaw (best in USA + Japan) or alaw (best in Europe and for international calls) encodings (about 500kBytes/minute) that are commonly used for SIP voice data and can be read by most programs.

With Oreka, audio file storage format can be set up within Oreka’s config.xml (Caution: do not choose native):
   <!– Audio file storage format: choose from: native, gsm, ulaw, alaw, pcmwav –>
   <StorageAudioFormat>pcmwav</StorageAudioFormat>

Converting to MP3

When publishing recordings, I’d suggest to produce .mp3-files. Oreka can’t do this on its own (at least the free version). I’m using WavePad to do the job: Drag your .wav file to WavePad, then click Effects, Dynamic Wave Compressor…, Threshold -24dB, Ratio 5:1, Limit 4dB, OK, then Save File As…, MP3, Constant Bitrate, 16kbps, Mono. You’ll end up with tiny files whose quality is superior to the one produced by commercial conference recording systems. 

Using an External Hardware SIP Phone

When using an external SIP phone (my favorite is the Thomson Speedtouch ST2030), for Oreka to successfully record your phone calls, it is required that Oreka “hears” all the data being sent from and to your SIP phone. That’s quite easy when using a soft phone on the very same PC that Oreka is running on, but will be more complicated when using an external hardware SIP phone. Current computer network equipment uses network switches to interconnect devices. Switches are smart. They know how to direct network data packets, so that reach their intended receivers - and only those. Let’s assume you’ve connected three devices to your switch (the switch itself possibly having been integrated within your DSL router):

  1. Your DSL router
  2. Your SIP phone
  3. Your PC (with Oreka installed and trying to eavesdrop your phone calls) 

Now, when you place a phone call, your switch will forward voice data from the internet to your phone (and vice versa). Your PC however will not receive any data sent from or received by your phone, effectively deafening Oreka. Although Oreka has instructed the network card within your PC to listen for any traffic (including the traffic that’s not destined for your PC), you won’t be able to record any phone call at all.

So are we stuck yet? Depends. If you are using a VOIP-DSL router where you have plugged your analog phone(s) into, the answer is yes. Read no further. Either look for conferencing services (e.g. Basement Ventures Free Conference Call Services) or analog taps that go in between the cable from your phone and to its handset (e.g. the Radio Shack Mini Recorder Model 43-1237 or the JK Audio THAT-1). However, if you are using a VOIP phone (one that uses Ethernet and does the SIP itself), you’ll get away by replacing your switch with a hub.

Provided you are using a SIP VOIP phone, you’ll either need a switch that features port mirroring (quite expensive) or a network hub, which forwards any data received on one of its ports to all other ports. As far as I know, hubs are no longer being manufactured at all, so you’ll either have to snatch one from a museum or get a used one from eBay. I’ve successfully tested the Netgear FE 10x and DS 10x hubs, both readily available and very inexpensive.

Credits

Tom Keating’s article VoIP Call Recording within his VoIP & Gadgets Blog has provided a plethora of invaluable information and thus served as an ideal starting point - a must have!

18 comments.

Bruce Kaskey

Comment on May 5th, 2008.

Reiner - thanks for using oreka, if you have any specific questions concerning oreka or orecx, please send us an e-mail Also do you have Tom Keatings e-mail?

Reiner

Comment on May 5th, 2008.

Hi Bruce,

first I have to confess my admiration for Oreka/Orecx: I’ve only just scratched Oreka’s surface and I’m very much impressed by its ease of use: It’s working like a charm - exactly as advertised (and even on Windows XP Embedded with just a little bit of tweaking, as in my case). I still have to explore more complex use cases - involving web gui and the like.

Regarding Tom’s email - no I don’t have it (I’m not a buddy of his). If I were up to contact him, I’d have a look at http://www.tmcnet.com/tmclabs/. Tom’s phone number is right there - waiting for customers and contracts :-)

Take care,
Reiner

Mahendra

Comment on September 25th, 2009.

I’ve installed Oreka and done what is instructed in the readme file. But I still do not get recordings in the Orkaudio Recordings Folder no is there anything in the tape list. My config file is as follows…


./AudioRecordings


VoIP.dll
Generator.dll
SoundDevice.dll
audiocaptureplugins/


gsm


yes

localhost
false
1000

false
20

\Device\NPF_{F856D2A6-8DF2-4496-9AF0-261CD6D1CADC}
10.20.0.129










3
20
sine.8KHz.pcm.wav

and my log looks somthing like this..

OrkAudio service starting

2009-09-25 11:17:12,187 INFO root:93 - Loaded plugin: ./plugins/RtpMixer.dll
2009-09-25 11:17:12,187 INFO immediateProcessing:53 - thread starting - queue size:10000
2009-09-25 11:17:18,593 INFO root:87 - Loaded plugin: audiocaptureplugins//VoIP.dll
2009-09-25 11:17:18,593 INFO batchProcessing:129 - thread Th0 starting - queue size:20000
2009-09-25 11:17:18,593 INFO packet:835 - Initializing VoIP plugin
2009-09-25 11:17:18,656 INFO packet:753 - Available pcap devices:
2009-09-25 11:17:18,656 INFO packet:760 - * \Device\NPF_GenericDialupAdapter - Generic dialup adapter
2009-09-25 11:17:18,656 INFO packet:760 - * \Device\NPF_{F856D2A6-8DF2-4496-9AF0-261CD6D1CADC} - Intel(R) 82566DM Gigabit Network Connection (Microsoft’s Packet Scheduler)
2009-09-25 11:17:18,656 INFO packet:781 - Successfully opened device. pcap handle:12b3640
2009-09-25 11:17:18,656 INFO packet:617 - Start Capturing: pcap handle:12b3640
2009-09-25 11:33:05,156 INFO sip:351 - INVITE: sender:10.20.0.136 from: RTP:10.20.0.136, to: rcvr:123.231.4.89 callid:

Can somebody tell me what more needs to be done..?

Reiner

Comment on September 25th, 2009.

Hi Mahendra,
I found out, that not all possible audio formats appear to be working. I’ll be mailing you my config.xml right now that’s working for me.
Another possible cause might Aureka attaching to the wrong network card. But as your log shows, it has at least seen the SIP invite, so it should see the voice traffic as well.
Regards,
Reiner

George

Comment on February 23rd, 2010.

Hi!

Thanks for this blog, it help me. One thing to ask you; I’m using Oreka with Magicjack and its work well, if I make call with my Magicjack phone Oreka creat an mcf file that it becomes a wav file. But If I receave a call, the mcf file does not become a wav file, it’s stay .mcf file and I cannot listen it! Can you help me!

Thanks

Reiner

Comment on March 1st, 2010.

Hi George,

sorry for being that late. No, I can’t imagine why the mcf would not be converted just for incoming calls (provided the caller uses an encoding Oreka understands).

You should have a look at the log files and try to find any suspicious differences between incoming and outcoming calls.

You may, if you wish, mail one of those log files (containing both an incoming and an outgoing sample) to me.

And then, there’s the Oreka User Mailing List. Maybe someone has suffered from the same symptoms as you and could provide a fix.

Regards,
Reiner

ctygehtuk

Comment on March 23rd, 2010.

HI
I’m using Oreka on the machine as an Ethernet bridge inserted in the Ethernet path. Oreka create files, but with extension .mcf. I’m setting “pcmwav” value on the “StorageAudioFormat” option, so why Oreka create .mcf files?

Reiner

Comment on March 23rd, 2010.

Hi Ctygehtuk,
Oreka always records native (i.e. bit data from the voice codecs) VOIP streams to .mcf files. After the call has ended, it then proceeds to convert the data to the format requested (e.g. pcmwav).
Regards,
Reiner

ctygehtuk

Comment on March 24th, 2010.

Reiner, thanks for your answer. I understand about .mcf files.

But, when call is ended the prosess of conversion is not started, however i set the “pcmwav” format. I mean I can’t see .wav file in the destination folder after call ended.
In log file I don’t notice any important errors.

Stefan

Comment on April 26th, 2010.

Hello
I just installed oreka hoping that I can track my skype calls, gtalk, etc.
But I can’t seem to find sounddevice.dll - it’s not installed by default, only voip.dll is there. Any idea where is this file or where to get it from?

Alok

Comment on July 2nd, 2010.

Hi,

I was just installed Orkaduio 1.2 free version. My problem is that its not creating the file greater than 23 MB, its showing the error ” ERROR tape:244 - [OLA] capture file 20100701_095536_OLA.mcf is over size limit (300000 KBytes) - ignoring new data”. Any idea about that how can i fix that problem?

angel

Comment on October 21st, 2010.

Hi,
i have been playing with Orkaudio GPL 1.2 for last few days and it works fine with SIP i just did not find a way to get native SIP callid instead orkaudio id. Doe enyone have some experience with Orkaudio and H323?
I have tried this and recording works, but there is no calling and called number. Instead number i got source and destination IP addresses. Any ideas or sugestions?

isychron

Comment on March 13th, 2011.

Hi
I have the same problem with ctygehtuk, i installed orkaudio and have my interface sniffed the sip traffic, however all recordings were not converted to wav files, hope there is someone who was able to solve it, I will appreciate all the help
below are my config, thanks to all

true
D:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\ROOT
VoIP.dll
audiocaptureplugins/
LiveMonitoring

gsm

yes

localhost
8080

BatchProcessing, Reporting, TapeFileNaming

remotepary, remotehost, localparty

\Device\NPF_{C19C9726-1E66-4458-AB54-EDFE6355D64F}

net 172.2x.0.0/16

10.4.x.2, 10.4.x.9, 172.2x.0.0/16
yes
yes
yes

Pankaj

Comment on March 24th, 2011.

Hi,

I have installed Oreka 1.2 on Centos 5.4 and its rcording files in .mcf format. Please guide ho make them converted to .wav.

Bernardo Torres

Comment on May 13th, 2011.

If your orkaudio is configured correctly and can capture common VoIP traffic (SIP + GSM), but not the traffic that occurs in your network, then you have a conversion problem.

varun pratap Singh

Comment on October 17th, 2011.

Hi Everybody,
Can I anybody tell me how to configure the OrkAudio like that it replieas the SIP INVITE coming to system with OrkAudio with 200 OK . And then the call is established it reocrds the RTP packsts comning to it.

Eugene

Comment on February 22nd, 2012.

Hi guys my orkaudio works perfectly most of the times but there are the rare occasions when it does not convert the mcf file to wav, ow can i do that manually

Omkar

Comment on March 26th, 2012.

I am trying to use OrkAudio for my project but I don’t know how to use it. Does it work with Skype calls too? Do I need some additional hardware to record my calls. My log file shows that it tries to connect to a server but fails. Can someone send me their config file and how you went about installing it? — Thanks a lot

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