The carriers are looking for verbiage either in your privacy policy which should be linked on your opt in form or the verbiage itself can be on the opt in form.

We consistently see this get verbiage get approved:
Your mobile information will not be sold or shared with third parties for promotional or marketing purposes.

So something to that effect is the bare minimum accepted by carriers.

Also, ideally the carriers like to see a more robust sharing verbiage such as:
​
All the above categories exclude text messaging originator optin data and consent; this information will not be shared with any third parties.

We will not share your opt-in to an SMS campaign with any third party for purposes unrelated to providing you with the services of that campaign. We may share your Personal Data, including your SMS opt-in or consent status, with third parties that help us provide our messaging services, including but not limited to platform providers, phone companies, and any other vendors who assist us in the delivery of text messages.

It is important to note that the verbiage needs to cover any method of transfer so if it just says the mobile data won't be sold, that is insufficient as it needs to cover sharing as well which could mean being transferred without any sale such as between affiliates or friendly businesses, which is prohibited under 10dlc.