1-800 calls go directly to voicemail on my new iPhone SE

Thanks for posting in the Apple Support Communities BiliyT,

It sounds like you may have Silence Unknown Callers enabled. The following section provides information on the feature:

With iOS 13 and later, you can turn on Silence Unknown Callers to avoid getting calls from people you don’t know. This blocks phone numbers that you've never been in contact with and don’t have saved in your contacts list. If you’ve previously texted with someone using their phone number or if a person has shared their phone number with you in an email, a phone call from that number will go through.

Detect and block spam phone calls

To turn Silence Unknown Callers off, go to Settings > Phone, then scroll down, tap Silence Unknown Callers, and turn the feature off.

We hope this helps!