 calls. IP Telephony for Small Organizations and Branch Offices: A System in a Box IP telephone systems designed for small to midsize businesses have almost all of the features and functionality of their large-enterprise cousins, including provisions for redundant key components. However, because they support fewer users, in many sys- items, the server and gateway components fit into a single rack-mountable device or small cabinet. Cisco Systems' diminutive IP PBX fits inside a router. When IP telephone systems are installed in small branch offices, the branch some- times routes all of its outgoing calls through headquarters by using a Wide Area Net- work (WAN) link and receives incoming calls through its own local phone lines. In addition, voicemail, contact center, and UC software are usually located at the head- quarters site. The remote system site often has backup outgoing lines in case the link to head- quarters is down. If this occurs, the system will automatically fail over to local tele- phone lines for outgoing calls. If there is no local backup, callers will need to depend on their mobile phones. Softphones and Portability A softphone is software with which people can use their computer to make telephone calls (see Figure 2-5). For privacy and noise abatement, they usually use headsets. Features such as hold buttons, caller ID, and message waiting alerts appear on their PC screen. Savings on telephone hardware and increased mobility for users are among the advantages of softphones. If the softphone is on a laptop, staff members can use the softphone anywhere on the corporate network or remotely if remote access is enabled. Mobile employees such as salespeople often use hardware-based phones at the office and softphones when they work from hotels or home offices. Many manufacturers integrate softphones with office software such as Micro- soft Outlook SO that they have access to collaboration software, instant messaging, IP Private Branch Exchange Architecture Figure 2-5 An Avaya integrated tablet comput