The document summarizes research on integrating encryption modules into the Sipdroid VoIP client app to enhance security. Key points: 1) The research integrated encryption algorithms like AES, DES, and RC4 into Sipdroid to encrypt VoIP call payloads. 2) Testing measured the performance of encrypted Sipdroid, finding a small increase in delay but no significant impact on packet loss or throughput. 3) Encrypted communications captured via Wireshark could not be decoded, demonstrating the integration successfully protected calls from passive eavesdropping.