When you are building a text list to send text messages to a large number of users, you will need to make sure that they opt-in manually. Even if you used a previous messaging service that users opted-in to, users will still be required to opt-in to your new list. Therefore, it is not possible to bulk-upload or import subscribers to your text list.
While manually re-collecting your subscribers can be time consuming, it is the law. Mobile marketing compliance laws are in place to help protect consumers from unwanted spam. Any business that fails to comply with these regulations can face fines, and even civil or criminal charges.
Alternate Methods to Quickly Build Text Subscribers
While you can't bulk-add users to your list, there are some workarounds to quickly build your list.
Send an Email Blast to Your Subscribers
Do you have an Email List built out with subscribers? If so, then you have access to a large number of engaged contacts who you can reach out to all at once. Send an email to your subscribers urging them to sign up for Text alerts. You can include the opt-in instructions in the email body to walk them through the sign-up process.
Collect Text Subscribers on Your Website
You can add some HTML code on your website to embed a button that subscribes users to your list. If a user is on their phone or mobile device, they can click the button to opt in to your list.
If you run a brick-and-mortar business, you may wish to share your opt-in keyword on in-store signage, print-outs, or on business cards. When your customers visit you in person, it's a good time for them to opt-in while you are at the top of their minds.