Phone companies make lots of money charging for each SMS aka Text message. When sending texts to other iOS users, your iPhone’s built-in Messages app can route text messages over your dataplan, avoiding any SMS charges by your phone company and saving you money.
MacLife has a detailed post on this topic:
- , Cory Bohon, Maclife.com, Feb 25 2013
iMessage background information:
- ,听补辫辫濒别.肠辞尘/颈辞蝉/尘别蝉蝉补驳别蝉
More tips:听