Currently common shielding methods are
1. Shield communication signaling port
2. Shield softswitch platform or landing gateway IP
3. Block the VoIP protocol (filter packets, any packets containing VoIP protocol fields are deleted or interfered directly)
4. Shield UDP port
For common shielding methods, the VOS system can flexibly increase the signaling port. At the same time, the VOS system has long proposed the VOS encryption specification and is fully disclosed. Any gateway manufacturer can implement the encryption of the terminal and the VOS system according to this specification. At present, the gateways that can be encrypted with VOS are: Shenzhen Deborah, Shenzhen Yizheng, Beijing Datang, Shanghai News, Hangzhou Sanhui, Dingxin Tongda, Beijing Tongoda, Shenzhen Houtian, Shenzhen Guangzhao (Shangyang), Shenzhen Yuanchuang.