In plain English
It is something extra added on top of the main mobile plan instead of being part of the basic package. It can be an extra service or an extra allowance, and it usually costs more.
In context
Here, “add-on” names an optional extra service or allowance that can be included with the mobile plan, usually for an extra charge.
- Situation
- Choosing mobile plans, allowances, roaming, fair-use, and add-ons
- What it communicates
- names an optional extra during plan checkout.
Meaning limits
The term by itself does not say what the extra includes or exactly how much it costs.
Examples
“Rather than upgrade her whole phone plan, she bought a data add-on for an extra monthly charge.”
“The family plan now has an international calling add-on.”