PortSIP

PortSIP CE is the newest free softphone application from PortSIP, it's built base on PortSIP VoIP SDK, allowing users to enjoy multimedia communications in a dynamic way.

PortSIP CE works seamlessly with your internet connection – you can chat away with free calls and never worry about cost, time or distance. It including great features to help you stay in touch with friends, family and co-workers, share your thoughts and views and find the information you need. You can use it on your PDA

PortSIP CE is a VOIP softphone that running on Windows Mobile 5.0/6.0, allows you to speak with any other softphone , any stand-alone IP-phone, or using Internet Telephony Service Provider (ITSP) with any traditional wired or mobile phone. It supports SIP and is fully inter-operable with most major VOIP vendors and ITSPs.

Standard Features
Support platforms: Windows Mobile 5/6
Support Device Screen: QVGA(320*240),VGA(640*480)
Support servers: Cisco CallManager, Open SER, SER, Asterisk, Portaone, Radvision, Nortel, Rainbow, Avaya and other SIP Platforms.

Switch between earpiece and load-speaker(Does no support some devices, likes Samsung I708)
Audio call: G.711 aLaw/uLaw, GSM, G723.1, G729.
Call transfer: Blind transfer
Call hold, mute speaker, mute microphone.
Audio record: record audio as wave file.
DTMF support: Send DTMF tone(RFC2833 and SIP INFO method), detect DTMF tone(RFC2833 and SIP INFO method).
Silent Ringtone
Acoustic Echo Cancellation
Automatic gain control
Comfort Noise Generation
Voice Activity Detector
STUN support
Outbound proxy server support
Jitter buffer
Freeware

Attention!
Having PortSIP installed is not enough to talk except over your local network. You have to obtain an account with any ITSP like Vonage or SipIptel.org, or install your own VoIP server.

PortSIP