If you want to use your phone to connect to the audio, you need to make sure GoTo Meeting has the right audio mode selected. Otherwise, it might try to connect you using both audio modes.

See How do I connect to audio from my phone? (Classic) to learn how to select the correct audio mode.

The organizer chooses which audio options are available for each session, so it's possible that not all options will be available in the session you are attending.

If you do you not see the Phone Call option, the organizer likely disabled it for this session (or it's not available on their subscription plan) and you will need to use a different method to connect to audio.

If you are unable to connect to the session at all, it's possible that your telephone service provider is experiencing issue. Try using a different phone, or connect using the internet instead.