How to install and configure a SIP VoIP softphone for use on a

low bandwidth dialup connection

A dialup internet connection has very low bandwidth in the direction from PC to Internet (that is your voice data to the remote receiver). It has better bandwidth in direction Internet to PC but the problem with VoIP is that it requires good bandwidth in both directions. The symptoms are that you can hear the remote party clearly, but the remote party cannot understand you because your voice is chopped and distorted.

The solution is to use a good codec to compress and minimise the data. The remote party will need a matching codec. Codec is short for compressor/decompressor, and is any technology for compressing and decompressing data. Codecs can be implemented in software, hardware, or a combination of both.

Cycom Limited uses Grandstream BudgeTone 102 IP phones (hardware phones). They are a little too quiet on ring volume and can only store one service providers settings at one time and it is difficult to dial non-numeric SIP addresses. They support G723 codec and iLBC codec which are low enough bandwidth.

A suitable softphone to use to call us is SJPhone from SJLabs.com. You should download the MSWindows version which is not configured for any service provider to ensure you can access all the configuration settings and not be confused by strange GUI skins. Download version 1.5 here.

You download the installation program. For windows users this often gets stored on your desktop. You then run/execute the installation program. Then you can delete the installation program if it was on your desktop (it is called Sjphone-271d.exe or similar).

After installation the Sjphone will be running every time you computer starts and will have a little icon in your system tray at the bottom right of your screen. You can bring up the phone into an interactive state from this icon. It first appears as a kind of cellphone appearance.

First get rid of the fancy skin or appearance by clicking the “Options” button (disguised as a screwdriver tool button in the center of the GUI). The “Options” button will bring up a further GUI which will have a tab called “Skins”. From this tab, select “No skins”, apply/save and exit. If you cannot find an “Options” button, try a right mouse click over the status panel to see if you get a popup menu with “Options” as a choice).

Next time you bring up Sjphone, it should have a more conventional dialog appearance with well named buttons such as “Options”.

From the “Options” GUI, select the “Profiles” tab and then ensure that the “PC-PC SIP” is in use. If not in-use, then highlight it and click the “Use” button until it shows as in-use.

From the “Options” GUI, select the “Audio” tab and then click the “Compression Settings” button. Ensure the “SJ Labs iLBC Codec 30ms” is ticked and at the top of the list. Move it to the top of the list by highlighting it and then pressing the “Up” button a few times. Press OK.

From the “Options” GUI, select the “Audio” tab and then click the “Advanced Settings” button. Increase the driver buffer size to 100 or 128 ms. Press OK. Press OK.

You can check here for complete instructions.