Some restrictions apply when sending SMS messages:
Account Credit Limit
Your account has a spending limit configured to prevent bill-shock and runaway processes. When your credit limit is reached, messages will be held in a Credit Hold queue and your accounting administrator will receive an email notification.
Mobile Contact Number Limit
Broadcasts can include up to 50,000 mobile numbers. The maximum list file size is 25MB.
SMS Character Limit
When sending longer text messages (more than 160 characters) or messages containing special characters (emojis, accents), you may reach your character limit. The message will be truncated at your character limit. See the Sending Longer SMS Messages guide for information on increasing this limit.
The SMS Delivery Result Codes guide has useful information on SMS error codes.