The most innovative full IP based VCS on the market. R&S®M4ACS clearly separates red/secure from black/non-secure domains. Operators can simultaneously access two security domains with the same audio accessories and clear audio routing principles. The two security domains are separated by a TEMPEST Level A, Common Criteria BSI-certified R&S®Trusted Audio Switch. Each security domain has independent core equipment to access specific legacy and IP interfaces with distinct demarcation equipment.