Busy lamp field system for remote telephones and method for the same

A busy lamp field system for remote telephones, comprising:

• a plurality of switchboard systems, each switchboard system comprising:
• a private branch exchange (PBX) connected to the internet;
• and
• at least a telephone connected to the private branch exchange, the telephone housing having at least a busy lamp field (BLF) key set to associate with corresponding phone number of a remote telephone, wherein the remote telephone is a telephone of another switchboard system;
• an extensible markup language (XML) server connected to each switchboard system via the internet and having an up-to-time table used for storing phone status of each telephone in each switchboard system;
• wherein each telephone is connected to the XML server via the internet and periodically uploads to and stores local phone status in the up-to-time table, and each telephone retrieves the phone status of the remote telephone corresponding to the BLF key from the up-to-time table and displays the phone status via the BLF key.