BlinkenIsdnProtocolEnglish

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The Blinkenisdn protocol was used in early days to transmit the current state of two ISDN lines over a network.

UDP packets of 2 bytes are sent periodically (e.g. every second) and additionally on every change. Each byte represents the current state of a ISDN line.

The format of the UDP packets simply is:

+--------------+--------------+
| line 1 state | line 2 state |
| 0xFF         | 0x00         |
+--------------+--------------+

• line X state: a byte indicating the current state of the ISDN line X
  • 0x00: on hook
  • 0xFF: off hook, no key pressed
  • '0', ..., '9', '*', '#': the key currently pressed

The UDP port should be configurable at server and client side. The standard port is UDP 4242.