SJphone is a softphone that allows you to speak over Internet with any desktops, notebooks, PDAs, stand-alone IP-phones and even with any conventional landline or mobile phones. It supports both SIP and H.323 industry standards, and is fully inter-operable with most major Internet Telephony Service Providers (ITSP) and VoIP software and hardware.

For calling over the world you need to open an account with an IP-Telephony service and to get their service profile, or to make their SJphone profile yourself.
Advanced users may build their own Voice over IP networks using either an H.323 Gatekeeper, SIP proxy, IP-PBX, and other components. They can also connect to conventional telephones using H.323/SIP Gateways (such as Cisco 26xx/36xx/37xx/53xx).

SJphone Features:
SIP Compatibility
allows you to speak over Internet
1. directly with most other SIP-softphones and stand-alone SIP-phones (such as Cisco 7940)
2. with other people in your company through your SIP IP-PBX system or Proxies (such as Asterisk, Broadsoft and others)
3. with all other people around the world using most SIP ITSP accounts such as FWD (www.fwd.pulver.com)
4. with a regular telephone using most SIP Gateways

SIP features:
1. TCP support
2. TLS tunneling support
3. Full support for SRV/NAPTR records and transport layer enhancements
4. Concealed Caller ID
5. DNS support in the SIP stack

H.323 Compatibility allows you to speak over Internet
1. directly with any other H.323-softphones, and stand-alone H.323-phones.
2. with other people in your company through your H.323 IP-PBX system, such as Cisco Call Manager
3. with all other people around the world through any H.323 ITSP accounts
4. with a computer or telephone on a private network through a Gatekeeper
5. a regular telephone using most H.323 Gateways

Instant Messaging:
1. Jabber: Presence
2. Jabber: Simple Chat
3. Jabber: vCard Display/Editor
4. Jabber: Customizable Rules for Placing Calls from the Roster
5. Jabber: full support for TLS transport

Features that make SJphone Easy to Use:
1. Skins allow you to change the appearance of the SJphone Main panel
2. Call any host by its name or IP address
3. Proven Interoperability with most IT service providers (you can download profiles for some of them)
4. Fast Service switching between ITSP, IP-PBX, Gatekeeper, Gateway, or SIP Proxy settings and GUI
5. Contacts, call logs, and speed dialing
6. Outlook and Opera contacts
7. Call a computer or telephone on a private network through a Gatekeeper
8. Call transfer, hold, and mute
9. Can automatically accept incoming calls, or reject them immediately (the "Do Not Disturb" mode) or after a specified time
10. Automatic discovery of neighbor SJphones
11. Respondent list allows you to maintain and manage multiple calls
12. Dial pad to type in numbers and send DTMF signals, sent using the either as audio, INFO message, or out-of-band methods.
13. Audio Wizard that allows the user to set audio options easily and quickly.
14. Selectable Playback/Recording/Ringer devices switched on-the-fly
15. Input and output sound level indication and control
16. Automatically adjustable microphone volume
17. Automatically adjustable silence detection level
18. Support for most USB phones (several drivers are downloadable)
19. Support for most popular codecs: G711, GSM, iLBC, (G729 available only in commercial versions)
20. Support for wideband codecs
21. Noise reduction
22. Automatic Gain Control for microphone (software/hardware mode)
23. Automatic Echo Cancelling (AEC)
24. Automatic NAT detection
25. Calls from/to a private IP-network using the NAT traversal technology
26. Voicemail Message waiting indication
27. Vertical Service Codes

Features for Advanced Users:
1. Customized service profiles allow you to create your own profiles for calls through your H.323 Gatekeeper, Gateway, or SIP Proxy
2. Multisession calls
3. 3-way conferencing using different VoIP protocols
4. Manual codec selection
5. Support for extended H.323 address syntax
6. Support for advanced SIP URI syntax
7. Support for CallTo URL
8. Lost and out-of-order packet indication
9. Log window for operation monitoring
10. Media Engine statistics
11. Per-Call RTP statistics
12. QoS/TOS/DiffServ support
13. Advanced lost packet recovery, offering better sound quality over a poor connection.
14. Optimized processor usage for HT/Multicore processors
15. Remote support console
16. An SDK for developing third-party VoIP applications

The license of this software is Freeware, you can free download and free use this internet phone software.