To the naked eye, a Voice over Internet Protocol (VoIP) phone resembles any other telephone or cell phone product. However, it's actually a phone product that allow users to place voice phone calls over a computer's Internet network instead of a standard telephone network; thus, the term "IP Phone," or Internet Protocol Phone.Variations of mobile VoIP Phone products include: A standalone IP phone with hardware that resembles a standard mobile phone or analog phone product A Wi-Fi enabled mobile VoIP phone with hardware that resembles a mobile phone or a PDA; in the latter case, these types of PDAs may also be called smartphones (Besides Wi-Fi, other such IP phone network protocols may include SIP, or Session Initiation Protocol, and HSDPA, or High-Speed Downlink Packet Access) A mobile IP phone with fixed and mobile telephony convergence; i.e., the ability to switch between standard telephone/cell phone networks, computer networks, and other networks An Instant Messenger-enabled IP phone that supports communications from phone to PC and PC to phone Mobile IP Phone enhanced features include: Voice Mail Speed dialing Call waiting Call hold Auto Attendant – a feature that provides automated messages to callers and directs calls Call forwarding, or Find Me Follow Me VoIP phone operating systems include Symbian, Windows Mobile 6, RIM Blackberry, and iPhone OS, Linux, Palm OS Find VoIP telephone service provider product comparison resources An Internet phone service provider with the right features for your business VoIP phone will sell or recommend the right IP phone product for your business. Visit VoIP service provider websites Specific VoIP telephone service provider websites recommend compatible Internet Protocol phone products. Find a VoIP telephone compatible with your operating system Some users prefer specific operating systems such as Linux and RIM Blackberry. Get information on VoIP phones compatible with VoIP applications VoIP applications offer specific features that may be compatible with your business needs. Get product information on specific mobile IP phone system models Nokia is one of the pioneers in IP mobile phone technologies. Apple's iPhone is also becoming a player. Keep track of news and views about phone product developments in fixed and mobile telephony convergence where phone products have access to both landline and mobile networks. When buying an IP phone system with a free or low-cost mobile phone service provider such as Skype, be aware of current litigation in governmental courts centered on conflicts between VoIP services and traditional telecommunication and cable companies.