A Data Access Arrangement (DAA) is an electronic interface inside a PC and its modem to a public phone line. A DAA is additionally now and then called a Telephone Line Interface Circuit (or Module). DAAs are needed in any gadget that connects to the public exchanged phone organization ( PSTN ), including fax machines, private branch trade , set-top box , and alert frameworks. In addition to other things, the DAA secludes the electronic gadget from the higher voltage on the phone line. DAA hardware requires enlistment with the phone framework overseeing authority, (for example, the Federal Communications Commission in the U. S.). Be that as it may, most makers of modems and different gadgets assemble an all around endorsed DAA plan into the modem.