Connectivity Problems¶

Sometimes communication between end-points fails. What can be the reasons? Here is a short checklist:

Local Computer¶

• Firewall software. Check if no software blocks access to the ports used by your application

Internet Router¶

• SIP ALG enabled. Check of the router has any so called SIP support and disabled it.

Internet Provider¶

• Policy that blocks either SIP signalling or RTP media. You can try use another SIP service provider that provides access over TCP or TLS instead of UDP or is using custom ports.

SIP Service Provider¶

• Some provider requires use of STUN protocol so that the SIP devices uses a public IP address in the Contact header. This is wrong as such behaviour is explicitly discouraged by the standards.