As a result of some protocols of high security like SRTP protocol which is applied effectively in some occasions of quite high security requirements, here, propose an encryption algorithm based on one of the two major VoIP encryption algorithms which named H. 323. As a fact, the security of those existing communication solutions need high investment, give a substantial decline in system performance, as well as increase in the problem of voice traffic delaying, this algorithm can be used with fewer invest, smaller sacrifice performance for commercial purposes. First introduce the basic architecture of VoIP briefly, then give an analysis of the main-stream protocols, select the H.323 protocol and study the family of this protocol about VoIP application, and finally add encryption algorithm to the corresponding application. The algorithm is designed on the variability of algorithms instead of the complexity of the encryption algorithm. Thus, it can guarantee security on the basis of implementing simply and easily, consuming as small as possible and costing as low as possible.