SIP Services and Gateways:
- IPTel.org – SIP service, voicemail (delivered as PCM Audio to email)
- FreeOpenCall.com – SIP account, SMS callback service, PSTN gateway (attractive rates), refereral/affiliate program
- Ekiga.net – Ekiga.org‘s VoIP SIP service, multiplatform SIP client, STUN service, PC-to-Phone calls (payment via diamondcard.us)
- Express Talk recommended SIP providers
Software:
- Ekiga – simple, available for multiple platforms
- Express Talk VoIP Softphone – cool and powerful, freeware and commercial business edition
- SJphone