With currently more than 178 million users worldwide, the demand on real-time multimedia communication services (e.g. VoIP, video conference) grows steadily. However, whilst the protocols utilised in such communications are standardised, internal aspects are not. For example, if calling parties utilise incompatible media codecs or security mechanisms, a real-time multimedia communication cannot be established. The latter would result in either a failure to establish a connection or a plaintext connection that leaves the communication open to attacks. This paper proposes a novel technology independent security gateway for real-time multimedia communications which offers ciphering assistance for these terminals when they have incompatible security mechanisms and/or media codecs, allowing them to communicate in a seamless and secure manner despite their incompatibilities. The proposed security gateway operates across standard IP protocols and provides a flexible, scalable and robust system that is capable of managing the ciphering requirements of a modern communications system.