Aloha,
Can FreePBX v17 call out to domestic long-distance phone numbers?
Sure can.
What configurations do you apply to enable long-distance calling?
A SIP trunk
Could you explain why you think there may be a problem? From an Asterisk point of view there is no fundamental difference from calling local PSTN numbers, so I think you may have a fundamental misunderstanding of how VoIP is used (actually you didn’t constrain yourself to VoIP solutions, although nowadays they will probably be the preferred ones).
You will need someone to provide a service to access the PSTN in all cases.
So assuming you installed FreePBX 17 and you have extension to extension dialing working, yes ?
In order to dial off of your FreePBX (any external calling, in or out), you need to have a sip trunk by a sip provider.
Do you have a sip trunk set up (who is it) and can dial local numbers ? and when you say “local” where are you ? USA, Ireland, UK, etc ?
If you do have a sip provider set up and can dial off of your FreePBX, do they have any dialing restrictions ?
And of course an outbound route needs to exist to hand off to the SIP trunking provider. With the proper dial patterns defined. If local calling works, then perhaps the long distance dial patterns aren’t defined?