Using a separate virtual circuit identifier (VCI) for audio over IP has the potential to reduce latency on shared connections. ATM's potential for latency reduction is greatest on slow links, because worst-case latency decreases with increasing link speed. A full-size (1500 byte) Ethernet frame takes 94 ms to transmit at 128 kbit/s but only 8 ms at 1.5 Mbit/s. If this is the bottleneck link, this latency is probably small enough to ensure good VoIP performance without MTU reductions or multiple ATM VCs. The latest generations of DSL, VDSL and VDSL2, carry Ethernet without intermediate ATM/AAL5 layers, and they generally support IEEE 802.1p priority tagging so that VoIP can be queued ahead of less time-critical traffic.[16]
That being said, Grasshopper doesn’t offer any conferencing tools. For that, you’ll have to sign up for—Grasshopper’s sister company. This service offers both video and audioconferencing, but it does cost an extra $10–$30 per month. That’s another strike against Grasshopper, since most providers in Grasshopper’s price range include conferencing features.

Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet telephony, broadband telephony, and broadband phone service specifically refer to the provisioning of communications services (voice, fax, SMS, voice-messaging) over the public Internet, rather than via the public switched telephone network (PSTN), also known as plain old telephone service (POTS).

VoIP endpoints usually have to wait for completion of transmission of previous packets before new data may be sent. Although it is possible to preempt (abort) a less important packet in mid-transmission, this is not commonly done, especially on high-speed links where transmission times are short even for maximum-sized packets.[18] An alternative to preemption on slower links, such as dialup and digital subscriber line (DSL), is to reduce the maximum transmission time by reducing the maximum transmission unit. But since every packet must contain protocol headers, this increases relative header overhead on every link traversed.[18]

Still the pandemic won't last forever so keeping in mind core VoIP criteria is important, too. That means providing voice communications for employees at their desks. VoIP systems may also need to support a call center for sales, customer service, and support; and they often need to connect with and through a host of other communications channels, such as fax machines, video conferencing, conference calling, mobile communications, wireless handsets, and text messaging. On top of that, they're often expected to provide more advanced functionality through software, like shared meeting collaboration, voicemail to email transcription, and call recording. And lest we forget, many businesses still need a service that will connect to public switched telephone network (PSTN).  

Because of the bandwidth efficiency and low costs that VoIP technology can provide, businesses are migrating from traditional copper-wire telephone systems to VoIP systems to reduce their monthly phone costs. In 2008, 80% of all new Private branch exchange (PBX) lines installed internationally were VoIP.[9] For example, in the United States, the Social Security Administration is converting its field offices of 63,000 workers from traditional phone installations to a VoIP infrastructure carried over its existing data network.[10][11]

Other basic features to consider include the phone itself should your provider offer its own handsets. Many residential providers don't since their bridge devices allow them to work with old-style landline phones, but some, especially the larger and more business-oriented players, do offer special VoIP phones. These look and work the same as a regular phone aside from the initial setup process, which will require making sure the phone is connected to your Internet router in some way and then configured to access the VoIP provider's service from there.

From an end user point of view, the actual phone service works in the same way, you pick up the phone to answer a call or to dial a number just like with a landline service. Number porting means you can keep your existing phone number and simply switch it over to your new service provider. The residential VoIP providers take care of the call routing and you can call any destination and receive calls from anyone, just like with regular home phone service.