What is a data pack or add-on?

A data pack is extra mobile data you buy on top of your existing plan. The most common kind is a booster or top-up: when your daily allowance runs out before your cycle ends, you add a small pack (say a few GB) to keep going. There are also data-only packs designed for tablets, dongles or second devices that need internet but not calls, time-bound unlimited packs that give you unlimited data for a night, a weekend or a day, and larger bulk packs for heavy users or working from home. They all do the same basic job — more data — but differ in size, validity and price, which is what makes choosing the right one worth a moment's thought.