Click-through rate, or CTR, is the share of delivered messages whose recipient tapped a link or button. In RCS a button tap is reported directly; in SMS only a tracked link can be counted.
Measuring it on each channel
An SMS can carry a URL and nothing else, so CTR means the share of recipients who visited a tracking link. Link shorteners are common, but carriers increasingly treat public shorteners as a spam signal, so a branded domain is the safer choice. An RCS message from a verified RBM agent reports each suggested reply or action tap as an event with the postback data the sender attached, so CTR can be broken down by button without a landing page in between.
Why RCS usually scores higher
Three things change. The sender is verified, so the customer is not weighing whether the link is safe. The button is labelled with what it does, so the action is clear. And a rich card shows the product, appointment or amount before the tap. Vendor case studies report large CTR gains over SMS; the figures on this site are sourced on the pages that quote them, and the honest expectation is "materially higher", not a fixed multiple.
What it does not tell you
A tap is not an outcome. Pair CTR with conversion rate and watch both in analytics.