Troubleshooting

Registration

Not online / no green status icon

Registration is needed to receive calls. Enter the SIP server and check the username, login, password, and domain. Proxy and login are often required too.

Service unavailable, Bad gateway, Request Timeout: verify server and proxy details, ask the provider to whitelist your IP if needed, try UDP/TCP/TLS, or adjust the User-Agent in microsip.ini.
Forbidden or incorrect password: recheck credentials. Some providers need STUN when the PC lacks a public IP. Other causes: connection limits (disable "Handle IP changes"), a blocked User-Agent, IP blacklisting (try a VPN), or a PBX-side fault.
Internal server error with a SIP proxy set: append ";hide" to the proxy value.

Calls

Can't make a call

Microphone permission may need enabling in Windows privacy settings (error 450001 after Windows 10 1803).
Both an input and an output audio device are required, including for RDP.
Antivirus (e.g. Kaspersky) may need microphone access allowed.
Driver or audio device faults can cause initialization errors – update drivers or switch devices.
"Not acceptable here" / "Not allowed" means the PBX rejected a requested option (codec, encryption, caller ID). Check PBX logs or test a clean install.
"End of file": switch to UDP.

Timeouts making or ending a call

Test a clean install, verify account fields and number format/prefix, disable SIP ALG, try each transport separately, toggle "Allow IP rewrite" and STUN, try source port 5060, test from another machine or network, and check PBX NAT settings.

Missed incoming calls

Likely router inactivity timeouts. Lower "Keep-Alive" (about 9) or "Register Refresh" (about 58), without setting refresh too low to avoid PBX load.

No incoming calls (outgoing works)

Confirm the "Online" status. Check the router, try another connection such as a mobile hotspot, or test with another softphone to isolate a PBX issue.

No sound or one-way audio

Check antivirus settings and microphone access.
Configure the PBX for NAT (e.g. Asterisk chan_sip and res_pjsip settings).
Use "Allow IP rewrite" if the PBX cannot change, and disable SIP ALG.
Use one network connection or set the local IP manually, test a clean install, try STUN and ICE on or off, set source port 5060, or test another network.

Dropped calls

Use G.711 on both sides, disable SIP ALG, try each transport, toggle IP rewrite and STUN, check PBX NAT, or disable Session Timers as a temporary workaround only.

Slow call setup

Switch from TCP+UDP to UDP.

Freezes or crashes

Computer-side: check antivirus exclusions, sound/graphics/camera drivers, try MicroSIP Lite, try another audio device, or test on another PC.
App-side: disable logging and "Handle IP changes", reinstall with a settings backup, and enable features gradually.

Video calls

Crashes when starting video: update the video card driver and check hardware acceleration.
Green video: the video stream is not reaching the app, usually due to routing, NAT, or firewall issues.

Further help: FAQ, Documentation, or report a bug.