 IP telephones. It is used in landline and mobile networks. www.TechnicalPDF.com SLA (Service-Level Agreement) Often provided to customers by carriers that sell MPLS. The SLA defines service parameters such as uptime and response time. smart grids Upgraded utility networks for metering that can carry two-way messages on cellular networks between customers and electric utilities. A goal is to use energy more efficiently by monitoring usage patterns. SMS (Short Message Service) Short, 160-character (including header address information) text messages that can be transmitted between digital cellular telephones. SMTP (Simple Mail Transfer Protocol) The e-mail protocol portion of TCP/IP used on the Internet. Having an e-mail standard that users adhere to enables people on diverse LANs to send e-mail to one another. SNMP (Simple Network Management Protocol) The Internet Engineering Task Force (IETF) protocol standard used to monitor devices on IP networks. SNMP is used on most LAN monitoring software packages. softphone Telephone functionality on a personal computer in VoIP systems. People with softphone-equipped laptops can use their VoIP remotely. softswitch Used in converged enterprise and carrier networks that carry VoIP traffic. Softswitches are built on standard computer processors and use standards-based protocols, which makes them less costly than proprietary switches based on circuit-switched technology. Softswitches manage and control traffic in IP networks. www.TechnicalPDF.com SONET (Synchronous Optical Network) An older standard for multiplexing high-speed digital bits onto fiber-optic cabling. SONET converts electronic impulses to light impulses, and vice versa. Telephone companies use SONET to transmit data from multiple customers over the same fiber cables. spectrum Made up of frequency bands or airwaves that carry either analog or digital wireless signals. Spectrum consists of the multitude of invisible electric energy in frequency bands that surround the Earth and are used to transmit segregated radio