It doesn't have a sim. The Pebble's purpose-in-life was to be a good watch first. It complements your phone with smart features like notifications, automatically setting the time on your watch based on your phone, and syncing your calendar to Pebble's timeline. It's not a phone replacement like you're looking for, so Apple Watch is a good fit for you.

Still, I found my Pebble greatly reduced the time I spent looking at my phone because I didn't need to take my phone out of my pocket upon receiving a notification or to check the next item on my calendar.