11 min read
How to connect a softphone to FreePBX or Asterisk (PJSIP), step by step
FreePBX softphone setup over PJSIP: create the extension, match the Asterisk endpoint, auth and aor config, set NAT options, and fix 401, 403 and timeouts.
SIP
Posts about SIP, newest first.
10 min read
Introducing Darwvin Softphone: a SIP softphone that tells you why a call failed
Darwvin Softphone is a SIP softphone for Android and Linux, in Early Access. Its Call Doctor ranks the likely causes of a failed or bad-sounding call.
14 min read
SIP and NAT explained: STUN, TURN, ICE, rport and SIP ALG
SIP NAT traversal explained: why NAT breaks SIP calls, how rport, STUN, TURN and ICE help, why SIP ALG hurts, and the Asterisk PJSIP settings.
13 min read
SIP response codes explained: the complete reference with causes and fixes
SIP response codes from 1xx to 6xx with RFC 3261 meanings, the real causes of 401, 403, 480, 488 and 503, and how to fix each one.
11 min read
SIP trunks, hosted PBX and softphones: VoIP basics for small businesses
SIP trunk vs hosted PBX vs softphone for small businesses: what each one is, how they connect, what drives the cost and how to choose.
11 min read
One-way audio or no audio on VoIP calls: causes and step-by-step fixes
Fix one-way or no audio on VoIP calls by checking SDP addresses, SIP ALG, blocked RTP ports, symmetric RTP, codecs and hold, with captures and Asterisk fixes.
10 min read
Zoiper alternatives in 2026: SIP softphones for Android, desktop and Linux
Zoiper alternatives in 2026 compared by platform: Linphone, MicroSIP, Bria, Groundwire, Jami, Telephone and Blink for Android, Windows, macOS and Linux.