At this time, 160 characters is the industry-supported standard maximum for text messages across all carriers/mobile service providers and phones in the U.S.
Some smartphones such as the iPhone and the iMessage app have supported longer messages for years, but there is still a small percentage of wireless subscribers who rely on older phones without those capabilities … and the governing body that regulates these standards hasn’t changed them in several years as a result.
An easy workaround for this issue is to set up a message flow: First, use a keyword’s auto-confirmation message to provide the main content and include a link to a website or other media where the rest of your message, call to action, coupon, form, etc. is hosted.
Alternatively, you can use a keyword’s auto-confirmation message to provide the main content, then go to Messaging in your dashboard and create a series of autoresponders that are timed to provide the remaining content in your preferred sequential order.
You can pre-schedule autoresponders to go out a few hours, days, months, or even years in advance!