Zoiper is a software-based phone (softphone) that turns a computer or mobile device into a telephone. Instead of using a traditional phone line, it connects to a VoIP service provider or an on-premise PBX (Private Branch Exchange) like Asterisk, FreeSWITCH, or 3CX.
Zoiper has been available in two primary editions:
| Feature | Zoiper 3.5 | Zoiper 5/6 (Modern) | |--------|-----------|----------------------| | Video calls | ❌ No | ✅ Yes | | Push notifications (mobile) | ❌ No | ✅ Yes | | Modern codecs (Opus, G.722) | ❌ No | ✅ Yes | | TLS/SRTP encryption | Partial / old | ✅ Full | | Auto‑configuration (QR, provisioning) | ❌ No | ✅ Yes | | Dark mode / modern UI | ❌ No | ✅ Yes | zoiper 3.5
Security note: Zoiper 3.5 uses older TLS and crypto libraries. It is not recommended for sensitive business calls over the public internet unless used inside a protected VPN.
Before installing Zoiper 3.5 in a corporate environment, consider the following: Zoiper is a software-based phone (softphone) that turns
Security Vulnerabilities: Zoiper 3.5 was last patched around 2016. It does not support modern TLS 1.3 encryption. Your SIP password could be sniffed on a public Wi-Fi network. Never use 3.5 over public internet without a VPN.
The "Ads" in Free Version: The free version displays a banner ad. In 2024, the ad servers for Zoiper 3.5 may be defunct or redirected to malicious domains. Either upgrade to Pro (if you have a key) or switch to the free version of Zoiper 5, which uses safe, internal ads. Security note : Zoiper 3
License Transfer: Zoiper 3.5 Pro licenses are locked to the email address used at purchase. You cannot transfer them. If you lost your key, Zoiper support will not re-issue keys for v3.5 (they will offer you a v6 discount).
Zoiper 3.5 is a version of Zoiper, a cross-platform Voice over IP (VoIP) softphone application designed for making voice and video calls over the Internet using SIP (Session Initiation Protocol) and IAX (Inter-Asterisk eXchange) protocols. As a mature softphone product, Zoiper targets business and personal users who require reliable SIP/IAX connectivity, integration with PBX systems, and a user-friendly interface across desktop and mobile platforms. Version 3.5 builds on prior releases by refining usability, expanding codec and security support, and optimizing performance for modern network environments.