In a circuit arrangement for PCM telecommunication facilities, especially PCM long distance exchange facilities with several synchronous pulse clock controlled transmitters for common transmitting chanel, information from different transmission processes flows over a transmitting channel common to all transmitters. In addition to the transmitting channel, a test channel is provided. For the prevention of simultaneous transmission and a co-mingling together of information, each transmitter transmits its own binary coded address to the transmitting channel always before a message as well as to the test channel and receives back the total information after combining on the test channel for comparison, bit-by-bit with the actual address information transmitted by it. In the event of accidental simultaneous transmission start by a transmitter, in case of character inequality on the test channel between two simultaneously transmitted bits, the binary character of the one type always asserts itself against the binary character of the other type. A transmitter interrupts its transmission in the event of character inequality. The assertion principle is limited to test channels while the transmission of both types of binary characters to the transmitting channel is relatively low ohmicly.