| > | | | | to an IP address on a first-come, first-serve basis. This |
| | | | is a basic fact about the Internet, although certain |
| VoIP is a relitavely new technology and can have | | | | services allow for the "prioritizing" of packets by |
| some drawbacks compared to utilizing an analog | | | | networking hardware and software. This means that if |
| telephone including problems related to power, clarity, | | | | there are not enough resources or bandwidth to read |
| and delay. This difference leads to many advantages | | | | all the packages at once, packages will be put in line, or |
| and drawbacks. The main advantage of the system is | | | | in a queue. If this queue becomes too long and |
| that it uses a technology that is new and inexpensive, it | | | | overload, intolerable latency may be the result. |
| has higher call quality, and it works over both normal | | | | Solutions to this may include increasing the bandwidth |
| and internet networks. Despite these advantages, | | | | of a connection; though it is not always possible to |
| there are some drawbacks to VoIP technology as | | | | keep packets from having to wait in line if there is a |
| well. | | | | very large amount of data for the type of connection |
| When the power goes out, a normal landline telephone | | | | utilized. |
| stays active. This means that it can still be used, as it | | | | If there are too many packets in the queue, causing |
| does not need to be connected to a power source. Its | | | | the queue to overload, then packets are "dropped" or |
| power source is provided by the phone company''s | | | | deleted from the queue by the TCP protocol, which |
| wires, as explained before. Because the internet does | | | | also lowers transmission speed to handle the |
| not transmit power, which cannot be turned into a | | | | congestion. The dropped packets are then |
| digital signal: when the power goes out, so does a | | | | retransmitted, making sure that the connection is still |
| VoIP phone. As a result, VoIP equipment needs to be | | | | made. VoIP does not use TCP because |
| powered from an outside source. This disruption of | | | | retransmission would lead to intolerable latency, and |
| service means that when the power goes down, | | | | dropped packets can be avoided by putting VoIP |
| users are not able to use their VoIP phones, which | | | | packets at the head of the line of bulk traffic, even |
| disrupts business and emergency communications. | | | | when the queue is overflowing, preventing latency and |
| Because a power outage can be the cause of a | | | | loss of service. |
| major disaster, it can be argued that a VoIP phone | | | | The receiver must re-sequence IP packets that arrive |
| without a power backup goes out exactly when you | | | | out of order and recover gracefully when packets |
| need it the most. | | | | arrive too late or not at all. Jitter results from the rapid |
| Further problems with emergency calling also exist. A | | | | and random changes in queue lengths along a given |
| normal analog phone number is tied to an address as it | | | | internet path due to competition from other users for |
| phone and the phone lines occupy physical space and | | | | the same transmission links. VoIP receivers counter |
| do not allow for dynamic changes in address. On the | | | | jitter by storing incoming packets briefly in a "de-jitter" |
| internet, however, an IP address is not a real thing ? it | | | | or "playout" buffer, deliberately increasing latency to |
| is a "soft" location. Though the address of the owner is | | | | increase the chance that each packet will be on hand |
| often attached to an IP address, this address can be | | | | when it is time for the voice engine to play it. The |
| difficult to find, it may be fake or wrong, or it could be | | | | added delay is thus a compromise between |
| outdated. This means that emergency services can, | | | | excessive latency and excessive dropout, i.e., |
| and indeed have been, sent to incorrect locations that | | | | momentary audio interruptions. |
| were be set to be using those particular IP addresses. | | | | Furthermore, voice, and all data on the internet, is |
| Furthermore, many IP address simply do not have a | | | | transmitted over the same wires using the same |
| physical location. These include IP addresses that are | | | | protocol, with no owner or controller. This has allowed |
| gateways for private networks, which means that one | | | | for great freedom of expression on the internet, but |
| IP is the call-in, call-out IP address, while many different | | | | has also lead to its use for unsavory of malicious |
| IP addresses are contained within the private network. | | | | activities, as there are no gatekeepers to keep these |
| For this reason, there is no way to know which IP | | | | at bay. This means that the internet can be a fragile, |
| inside the private network made the call in or out to | | | | clumsy system at times, susceptible to congestion, |
| authorities. For a single household, this poses less of a | | | | denial of service attacks, and other issues that an |
| problem but, oftentimes, private networks could span | | | | analog system does not face. |
| large areas or cover entire buildings and even multiple | | | | When you pick up an analog phone and there are no |
| facilities. | | | | circuits available, you get a fast beep or an "all circuits |
| VoIP providers have made an effort to fix this | | | | are busy" message. This means that the system |
| problem by using a service called E-911. With this, the | | | | flat-out rejects any calls you make that would |
| subscriber supplies an address to be associated with | | | | overload the system. On a VoIP system, calls are |
| the phone number he or she will be using. This | | | | accepted indefinitely, which can lead to massive |
| information must be diligently kept up to date and | | | | overloading a huge degradation in voice quality and |
| changed if the subscribers move, leading many | | | | quality of service. Furthermore, phone systems are no |
| emergency professionals to disparage the practice as | | | | longer susceptible to hacking, and are not disrupted by |
| ineffective. Many VoIP telephones also contain a | | | | overloads. |
| battery backup so the phone will not go down | | | | In the continuing battle between VoIP and POTS, it is |
| immediately in the power cuts out, making it more likely | | | | likely that many of these issues with VoIP will be fixed. |
| that an emergency call can be made, should it be | | | | In the mean time, for many customers, POTS service |
| necessary. However, this requires that the user''s | | | | will continue to be the gold standard for reliability. |
| router and cable modem are also active, as well as | | | | These customers need the highest possible reliability |
| the computer, should the phone signal pass through | | | | for emergency calls, even if VoIP is cheaper and has |
| any of these devices, making VoIP inherently more | | | | far better service and audio connections. On the other |
| susceptible to power failure. | | | | hand, many consumers believe that the far lower cost |
| Quality of service can also be a problem with VoIP as | | | | of VoIP (about 50% of comparable POTS service), |
| well, especially when using slow or especially distant | | | | makes using the frequently less reliable technology well |
| networks. Packets are read by a computer attached | | | | worth the risk. |