AT&T applies sending limits based on the campaign type you have been approved for. Your maximum throughput is measured in TPM (Transactions Per Minute) and is shared by all phone numbers under a designated campaign. By default, most registered campaigns are assigned a maximum TPM of 240. However, this limit has the potential to move higher by means of secondary vetting. If your brand has received this 3rd party vetting, then the vetting score you were given determines the maximum AT&T sending limits based on the chart below.
For information on T-Mobile limits, click here.