@amy-boxleitner Yes - all SMS, no matter if to employees or customers.
I'm not sure if the text can be the opt in.
I think the documentation provided would need to describe the use case for internal SMS.
I'll ask internally to get a firm answer.

Yes, all employees must opt-in to receiving SMS from your company if you are texting their personal (not business provided) mobile device/ number. As a reminder, consent is implied to engage in a conversation with them if they message you first.

Otherwise, for conversational or informational messages (eg office closed) the level of consent that is required is just for them to state in some fashion (even verbally) they want to receive those messages. You could also send a quick email (for small organizations) or a Google Form (or equivalent) to capture consent.

While this consent does not need to be logged, if you do a Google Form or similar, it does provide an extra verification layer for your company.

Lastly, unfortunately unless you are already engaged in a conversation with them (see implied consent above), you cannot ask someone for consent by sending them a text message first. You would need to obtain the consent either verbally or via another "written" channel.

Regarding getting my customers opted in I have 1000 customers. I don't want to email or text each customer one at a time to get approval. How can send them all messages and upload the responses all at the same time. Also who and where do I upload the approvals. What does the accepted approval. Is it a email response to the opted in question. Is it the text thread asking them to opt in.