Just to also provide you with more information, Caller ID verification is now a legal requirement in the USA. So while we have a few months to enforce the new law, we've been rolling out the changes to all customers. Sadly, we can't disable the feature as it's a legal requirement for customers in the USA.
Currently, all Caller IDs should be existing, customers can enter their phone numbers and verify them to make them allowed in that drop-down list
Or you, as a reseller, can verify them on your own.
This is all part of a new US law that changes the liability of fraudulent phone calls. It's now resellers like you who are liable for your clients calls, not your clients (as it used to be). As the law only applies to Caller IDs, the simple fix is to verify the Caller IDs. Existing law (TCPA, etc) already requires that every phone number used for outbound calling must be able to be answered by a human when you call back. So every Caller ID is already required to be answered by a human, so verifying those numbers shouldn't be hard. The new law just changes who's liable.
https://www.natlawreview.com/article/fcc-acts-to-implement-requirements-section-3-traced-act -- just yesterday
https://docs.fcc.gov/public/attachments/DOC-364109A1.pdf -- "THERE WILL BE NO MORE WARNINGS"
This is a rather big deal law.