Lab1 4.3 question:PSTN access point
The Lab 1 4.3 HQ Call routing requests that 'the phones should use the on-site gateway as the primary PSTN access point'. Does it mean that they should have also secondary gateways? In real world if a phone can't access PSTN through on-site gateway (if it means the local gateway if I didn't make a mistake), is it usual to use a remote gateway to access PSTN (Although sometimes TEHO is a nomal implememtation)? Back to this issue, does this request imply that we MUST set a secondary gateway as the secondary PSTN access point, or it is just OK at least one primary PSTN access point?