This article describes how IP calls work in Grandstream GRP260X. According to the developers, a SIP account is required to register onto phones in order to run the SIP stack for the IP calls. The receiving endpoints need to disable the Use Random Ports option. The default SIP Port for IP calls is 5060.
- Register a SIP Account at Account 1
- Enable Direct IP Call under Phone Settings > Call Settings
- Disable Use Random Ports option under Phone Settings > General Settings
- Long press ‘1’ button for 3 seconds
- You may see ‘Direct IP Call enabled’ message on the screen, if not, just enter the receiving endpoint’s IP address to perform IP calls