This appendix describes the signalling for tandem mode operation of Digital Multiplexing Equipment with Low-bit-rate Voice CODEC (DME with LVC) in circuit-mode connection control. The scope of this appendix is for DSS1 to exchange information on the voice compression applied within preceding section so that the receiving network can know the information for controlling tandem mode operation of DME with LVC in case of interworking with DSS1 network. The process controlling tandem mode operation of DME with LVC in ISDN section by using e.g. ISUP [100] procedure is out of the scope of this appendix.