Original Commentary

Note the sound effect in the second panel, placed to imply that it is stopping Robert mid-word. If this were a more artsy comic, I would've had a much larger word-bubble, to hold what Robert intended to say in that panel, but had it be cut-off by the sound-effect (which would be inside the larger bubble) - Terrence

Modern Commentary
That phone ring is Isabel's handwriting font.

I really like the idea of using too-large word bubbles when somebody is cut off, sized for what they meant to say rather than what they actually said.

But also, space is at a premium. Back then, we were concerned about bandwidth. Now everybody reads comics on their phones. I like the concept, but in practice it's a bunch of dead space that might not read properly. - Terrence