Hello Lubomir,
On Thu, 18 Mar 2010 01:00:44 +0100, "Lubomir Schmidt" gentoo.lubomir@googlemail.com wrote:
How can i change the cable to get it working? What is a level-converter and where can i get such?
The level of the RS-232 interface is specified to be -3V..-15V for a logic one and +3V..+15V for a logic zero, typically -12V and +12V is used. The phone uses 0V and 3.2V. So you need a level-converter between the RS-232 port of a PC and the phone.
The simple solution is to use a ready-made data cable with a built-in level-converter, they cost around 9.00 EUR on ebay Germany including shipping, either as USB or RS-232 variant. If you really want to build your own level-converter, you can for example use the MAX232 IC. The MAX232 is for TTL level (0V and 5V), I think there is a variant for 3.2V available, however I am not 100% sure.
Best regards, Dieter