A private branch exchange (PBX) is a telephone exchange that serves a particular business rather than many businesses or the general public. A PBX also connects the phones of a private organization to the Public Switched Telephone Network (PSTN) through trunk lines. In general, the term "extension" is used to refer to any end point on the branch such as telephones, fax machines, modems, etc.

IDT offers solutions for PBX in the following categories: