Kara Waite, an English teacher at Bunker Hill Community College in Charlestown, Mass., made a rule for herself: For every political rant she posts on Facebook, she must pick up the phone and call a legislator.

“It’s kind of a swear jar for political action,” Ms. Waite said recently.

Ms. Waite, who volunteers for liberal causes and who created a widely shared document last week to teach others her methods, figures that a phone ringing off the hook is more difficult for a lawmaker to ignore than a flooded inbox.

Activists of all political stripes recommend calling legislators, not just emailing — and certainly not just venting on social media. Several lawmakers, along with those who work for them, said in interviews that Ms. Waite is right: A phone call from a constituent can, indeed, hold more weight than an email, and far outweighs a Facebook post or a tweet.

To understand why, it helps to know what happens when someone answers the phone at a legislator’s office.