We recommend keeping your groups to 22,500 contacts or less. Here's why:
The first reason is that really large files will cause the system to time out. Currently, the threshold for groups timing out is 50,000 rows. If your file is larger than 50K you will see the following error:
"CSV TOO LARGE. Campaigns can target a maximum of 22.5k valid phone numbers. Your CSV has more than 50k rows. Please split your CSV into multiple files and try again."
The other reason is that ThruText messages are sent from local cell phone numbers that we obtain via a third-party provider, Twilio. During the campaign creation process, you specify up to 3 area codes or regions from which you want those local numbers to be obtained. Twilio has a limited supply of phone numbers for each area code. To help ensure high deliverability rates, we obtain one local phone number for every 250 contacts. When you target a campaign to a large group, Twilio may have insufficient phone numbers in the 3 area codes or regions you select, which will cause the campaign to not launch and display a message indicating that not enough numbers are available.
22,500 contacts is a group size for which you should be able to consistently obtain sufficient local numbers, provided that you select 3 area code / regional options in the campaign process.
If your group is between 22,500 and 50,000 rows, you will see this warning:
"WARNING. Campaigns can target a maximum of 22.5k valid phone numbers. Your CSV has more than 25k rows. If your group has more than 22.5k numbers after validation, the group will not be usable for direct campaign targeting."