Blocking country codes but allowing long distance calls

[woo60420]

How does one allow long distance calls while also blocking international calls that have similar or the same numbers in the area code? For instance to call the area code here in the states of 660 i have to allow calls to Thialand to get the call to connect. Thanks

 

[sip.bg]

Either based on dialed number length or on international prefix (00 in Europe, 011 in USA).

 

[leejor]

There are several examples here...

https://www.3cx.com/blog/voip-howto/outbound-rules-a-complete-example/