Design of a VoIP Media Stream Encryption Device

The design of a VoIP media stream encryption device based on ARM9 CPU is introduced. The device can be deployed between the Soft Switch or IP-PBX and the VoIP terminal, dedicatedly used for the encryption/de-encryption of the VoIP signal and the RTP voice packet. As an illustration, the encryption flow of the packet is described when the VoIP protocol is SIP and the encryption algorithm is RC4. Then a test is implemented to compare the packet before the encryption and after that, the effectiveness of the design is proved.