When pressing DTMF 9 can you hear a sound?
If no the tests will need to continue with a different cellphone number, but not Iphone users.
If it works and you can hear a sound, then try override Iphone users from DTMF 9 to DTMF 2. Follow the link for a step by step guide to overriding triggers: https://combcomm.atlassian.net/wiki/spaces/PRODUCTS/pages/1466138638/Trigger+overrides
Once completed dial *#0003 on the unit from the cellphone number of the intercom to test.
If the resident presses DTMF 9 on their phones and ALL residents cannot open gate, then the wires for the relay will need to be tested. This is to be done by the installer.