The PRI Dialplan and the PRI Local Dialplan in the channel group section of a PRI have to do with caller ID and the TON or Type of Number. The Type Of Number is the dial plan or format that is used when setting or receiving caller ID. What these settings do is set the called (number dialed) and calling number's (the Switchvox on an outbound call) caller ID Type of Number format. Depending on what the provider requires you may, on very rare occasions, need to set either or both of these settings to Unknown from the default of National ISDN. These settings should only be changed on very rare occasions and usually only to get outbound calls to work.
Usually the symptoms are that long distance calls will work and local will not or vice versa. If you see this it is always best to try the Unknown TON as most providers who do not use the default National ISDN will allow the unknown.