| APO |
Australian Post Office. |
| APT |
Anglo-Portuguese
Telephone Company. |
| BPO |
British Post Office (the expression used in technical
journals). |
| GPO |
General Post Office (known internationally as BPO). |
| P&T |
Posts & Telegraphs Department (of the Irish Republic). |
| NTC |
National Telephone Company (active in the UK until 1912). |
| NZPO |
New Zealand Post Office. |