When you purchase a list of numbers, you are really going after the attached consumer data. You cannot use the actual numbers to grow your list, but when an owner of a purchased number does opt-in to your SMS campaign, you can connect the data to the subscriber. This will allow you to target messages with content that will result in a higher success rate.
As the name implies, shared virtual numbers are shared by many different senders. They’re usually free, but they can’t receive SMS replies, and the number changes from time to time without notice or consent. Senders may have different shared virtual numbers on different days, which may make it confusing or untrustworthy for recipients depending on the context. For example, shared virtual numbers may be suitable for 2 factor authentication text messages, as recipients are often expecting these text messages, which are often triggered by actions that the recipients make. But for text messages that the recipient isn’t expecting, like a sales promotion, a dedicated virtual number may be preferred.
You will have a greater chance of gaining access to their mobile number by following these guidelines. You can collect their numbers using a sign-up sheet at your register, asking them when talking on the phone, allowing them to submit a form on your website, or by giving them a number that they can text to subscribe to your SMS messages. Whatever you do, keep a copy of their permission to market to them via SMS, if you run into problems you will be glad you did.