Standard MMS and SMS rates apply based on your current AT&T rate plan. If you are on a plan that includes an unlimited number of texts like Mobile Share Value, you will not incur any additional charges when you use Advanced Messaging.
For Capped Messaging plans or Pay-Per-Use customers, you will also be billed at your current messaging rates. But please note, if you send a message with multiple attachments with Advanced Messaging, each file you attach as well as your text will be counted and billed as individual messages.
For example, if you type a text message and attach two photos, those would count as three separate messages (1 SMS and 2 MMS) for billing purposes. Files can be photos, videos, contacts, calendar items, or anything else you attach to your text message.