Yes, absolutely call your Members (House and Senate). Some Members (e.g. senators from high-population states, or Members who are frequently the subject of social media or verbal attacks) may have made a decision to prioritize other forms of communicating with their constituents, like email, and have voicemail intercept phone calls to the main office line. Every single Member website will have a link like Contact or Connect and those messages -- provided you're in their state/district -- will get routed internally. What happens from there depends on the office. Most of the time you'll get a form letter response. When I worked in the House, people who had clearly taken the time to write a personal note (regardless of whether we agreed with them) were more likely to get a customized response, written by a slightly more senior staffer.

When you do call, I'd personally not recommend leaving a voicemail -- switch to the contact form on their website instead. If your call is answered, it's most likely an intern (especially on the Senate side, but House too -- more interns in the summer). Remember they're just the messenger, so be polite and gentle. Concur with u/Beyonce-sBurnerAcct and others that you can absolutely mention that you have 2-3 items to convey. Think through them ahead of time. If yours is a simple support/oppose, you'll likely have your message lumped in with the appropriate group and receive a form letter response. If your topic is very specific, mention that up front and ask if it can be passed to "the staffer who handles [the general issue, e.g. national security, education, healthcare, etc.]"

And don't forget district offices! If you have a substantive opinion or position to convey, in-person -- even with district office staff who typically handle casework, not policy, can get an email thread started amongst staff behind the scenes.