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is often attached to an IP address, this address can be difficult to find, it may be fake or wrong, or it could be outdated.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