calls the pabx assigns the selection of a route between terminal 6 and terminal 310 to the new pabx node connection routes are established from terminal 6 to the new pabx node and from terminal 310 to the new pabx node finally connections between terminals 6 and 310 and the new pabx node are coupled together internally within the new pabx node reference is now made to fig4 in step 11 the user switches the mobile radio terminal 5 on and specifies 34 third party charge service 34 by entering a special code on the keypad of 5 including or referring to the telephone number of the pabx 311 in step 312 the user then enters the a and b numbers i e the telephone numbers of the terminals 6 and 310 into the mobile terminal 5 either via the keypad of 5 or by using a barcode reader for the a number and the keypad for the b number the user enters also a personal identification number pin if the procedure so requires then the user calls the pabx 311 by pressing the 34 send 34 key on the mobile radio terminal 5 the above described information is communicated to the pabx 311.