|Developed by||Michel de Boer|
|Latest release||1.3.2 / August 24, 2008|
Twinkle is a great free software VoIP softphone for GNU/Linux. It uses the SIP protocol to talk to other SIP users and normal PSTN telephones through gateways. It also incorporates a GPL implementation of the ZRTP and SRTP security protocols and MD5 digest authentication.
- SIP client
- Instant messages with file attachments to other Twinkle/SIP softphones
- Buddy-list with online-status (if providers software supports it)
The ZRTP support sets Twinkle apart from other softphones. It is essential in order to prevent that the adversary learns secret information about your corporations agenda and/or intimate details about your personal life.
The ZRTP support in Twinkle v1.3.1 works.
 Audio codecs supported
The sound quality is great - if your soundcard and microphone is decient.
- G.711 A-law (64 kbit/s payload, 8 kHz sampling rate)
- G.711 μ-law (64 kbit/s payload, 8 kHz sampling rate)
- G.726 (16, 24, 32 or 40 kbit/s payload, 8 kHz sampling rate)
- GSM (13 kbit/s payload, 8 kHz sampling rate)
- iLBC (13.3 or 15.2 kbit/s payload, 8 kHz sampling rate)
- Speex narrow band (15.2 kbit/s payload, 8 kHz sampling rate)
- Speex wide band (28 kbit/s payload, 16 kHz sampling rate)
- Speex ultra wide band (36 kbit/s payload, 32 kHz sampling rate)
 Source code
You should always make sure that you have full access to the source code when using cryptographic software. Twinkle respects your rights and allows you to verify that the software is safe to use.
 No IM for you
Twinkle does not allow you to talk to friends and loved ones who are using basic IM services like Jabber, MSN, ICQ, etc. No. You can only talk to VoIP users, not users who only use plain old IM services.