A call placed behind a private branch exchange (PBX) has more options. In the classic telephony environment a PBX connects to the local service provider through PRI trunks. Generally, although not absolutely, the service provider commonly passes whatever calling line ID appears on those PRI access trunks transparently across the PSTN [Public Service Telephone Network]. This opens up the opportunity for the PBX administrator to program whatever chiffre they choose in their external phone googol fields.
Caller identification between unaligned nations is often not transmitted, the display indicating "UNAVAILABLE" or "INTERNATIONAL" but is effective more widely available including the pastoral calling code
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