Internet telephony services enable the user to make real-time or close to real-time voice calls to telephones using an Internet connection and, typically, some type of software. In essence, the analogue voice signal undergoes conversion into a digital signal. The software transmits the digital signal and converts it back to an analogue signal at the destination. This technology creates both advantages and disadvantages.
Advantage -- Cost
Internet telephony services offer large cost savings over traditional long-distance and international telephone services. Some Internet telephony companies allow users to make computer-to-computer calls for free to other users of the software, making Internet service the only associated cost. For PC-to-Phone calling, Internet telephony companies generally charge a flat rate well below the costs for similar services using traditional phone service providers. Some companies also provide flat-fee, unlimited calling options for specific regions of the world, which can significantly reduce phone costs for businesses with international branches or for families with a member overseas.
Advantage -- Conference Calling
The majority of Internet telephony providers offer a conference calling feature, though the particulars of this feature, such as the total number of participants allowed, vary among providers. This option typically comes as part of the service package for no additional fee, giving it an advantage over traditional phone services.
Advantage -- Portable
Landlines lock the user into a single location to reap the benefits of traditional telephone services. Internet telephony services work anywhere the user finds available broadband access. Rather than assigning service to a specific location, Internet telephony assigns service to a specific account. Whether in Los Angeles or Southeast Asia, the software provides the user with access to the same service features.
Disadvantage -- Reliability
Like mobile phones, Internet telephony suffers from problems like dropped calls and audio distortion. The functionality of Internet telephony hinges on the quality of the broadband connection it uses. Sudden losses in bandwidth availability lead to voice distortion, lag time and abrupt disconnections. Older computers with slower processors and limited RAM (random access memory) may not be able to support Internet telephony calls or may yield substandard call quality.
Disadvantage -- Limited Emergency Call Support
Emergency services cannot trace Internet telephony calls since the calls do not originate at a physical location. This makes Internet telephony problematic in emergency situations. In order to limit this problem, the Federal Communications Commission set out rules requiring Internet telephony services to connect 911 calls to a Public Service Answering Point and to provide customer address information to emergency services. The FCC does note, however, that the very nature of Internet telephony limits the effectiveness of using it to make emergency calls.