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How is VoIP different from a landline?

✓ Verified Last reviewed by AnswerStack Next review due Dec 14, 2026

Direct answer

Every claim is sourced below

A traditional landline carries your voice as an electrical signal on a pair of copper wires that the phone company runs to your building. VoIP carries your voice as data over a network connection, and you reach the service through an account instead of one particular wire. That's the difference when "landline" means the old analog line. Many phones sold as landlines today are VoIP underneath, so the first thing to settle is which kind of landline you mean.

A landline can be VoIP

"Landline" tells you the phone is fixed at an address. VoIP tells you how the call travels. Those two descriptions can apply to the same phone.

The FCC's consumer guide to VoIP defines VoIP as a technology for communicating over Internet Protocol instead of traditional analog systems. The US definition of interconnected VoIP in 47 CFR 9.3 describes a service that needs a broadband connection and IP-compatible equipment at the user's location and can call ordinary phone numbers. A home phone service that reaches you as data through a fiber or cable modem matches that description, whatever the bill calls it.

The UK shows the overlap plainly. Ofcom, the UK communications regulator, describes digital landlines that run over a broadband connection, with the phone plugged into the router. The customer still has a home phone and a number, and the call travels as data.

So the comparison that follows is between a traditional analog landline and VoIP. If your landline already reaches you as data through a modem or router, the VoIP column describes it.

What changes between the two

What differs Traditional analog landline VoIP
How your voice travels As an electrical signal on a copper pair to the phone company As data packets over an IP network connection
How you reach the service Through the access line at one address Through an account, from devices set up on it
What you plug in An analog phone in a wall jack An IP phone, an app, or an analog phone with an adapter
Power A basic corded phone can draw power from the carrier's line The phone and network equipment need local power
Adding capacity Another analog line, where the carrier has one available Another user or device on the account, if the connection has room

Access, numbers and features

Most of the practical differences follow from how you reach the service. Analog service arrives on an access line, so the phone works where that line ends. VoIP service arrives through an account, so the service decides which devices ring. That's why the same business number can ring a desk phone and an app on a mobile phone, where the service supports it.

The phone number is a separate matter from the access. A number can be ported between providers, and between an analog line and a VoIP service. We explain what the account connects to in whether you need a phone line for VoIP.

The account also changes where the features live. On analog lines, a business got call transfer, hunt groups and extensions from a phone system on site or from features the carrier hosted. With hosted VoIP the provider runs those features in software. Atlantech Online's UCaaS page lists a Business Line starting at $12 per user per month. The card includes call forwarding, transfer, hunt groups and unlimited local and domestic long-distance calling. That's an advertised starting price for one provider's service, and a quote would set the actual bill.

Power and emergency calls work differently

A basic corded analog phone can keep working in a power outage, as long as the carrier's line stays powered. VoIP depends on power at your premises. The phone, the router and the modem all run on electricity there, and the network connection has to stay up as well.

The FCC's guide warns that some VoIP services don't work during power outages and that the provider may not offer backup power. Battery backup keeps calls going only if it covers every powered device on the path, the phone included, and only for as long as its capacity and the load allow. Where the service is set up to forward calls to mobile phones, that gives a second fallback.

Emergency calls differ for a related reason. An analog line sits at one address, so a 911 call from it comes from a known place. A VoIP account can be used from more than one place, so the service needs another way to know where the caller is. The method varies with the service. One is an address held on file, which FCC rules call a Registered Location and 47 CFR 9.3 defines as the most recent information the provider has that identifies the user's physical location. The FCC's guide also says some VoIP providers have limitations on their 911 service. We cover both subjects in whether you can dial 911 from a VoIP phone and how to register a VoIP phone for 911.

Some devices still expect an analog line

Phones are the easy part of the comparison. Fire alarm panels, elevator phones, security alarms and fax machines were built to plug into an analog line, and many still do.

Atlantech's POTS replacement service shows what those devices need once the copper is gone. Atlantech describes a managed appliance that gives each device an analog dial tone and connects to the network over broadband and 4G LTE. The page lists up to 24 hours of battery backup and says existing numbers can be ported to the service. The device plugs into the kind of analog interface it was built for. The copper pair behind that interface has been replaced by a box and a data connection.

The appliance has to supply what the analog line used to provide. The copper line delivered power and a fixed path to the phone company. The replacement supplies its own battery and a second network path for when broadband fails. A plain VoIP phone on an office network has neither unless you add them.

An analog interface doesn't make the service behind it identical to copper, so each device has to be checked on the new service. Ofcom's guidance says providers and device suppliers need to assess whether equipment such as care alarms will work on a digital line. Test an alarm on the replacement before the old line is disconnected. We list the equipment to check in which legacy devices are at risk when POTS lines are retired.

What stays the same

A call between an analog landline and a VoIP service that provides ordinary phone numbers works in both directions. The FCC's guide says that when you call a regular telephone number, the signal is converted back at the other end and the person you call needs only a telephone. An analog line and that kind of VoIP service both use ordinary phone numbers and reach the same public telephone network. We describe that network in how the PSTN works.

Sources

47 CFR 9.3, Definitions: Interconnected VoIP service

Legal Information Institute, Cornell Law School

Independent Verified Sep 14, 2026 Supports: Definition of interconnected VoIP: real-time two-way voice, broadband connection from the user's location, IP-compatible customer premises equipment, and calls to and from the PSTN; definition of Automatic Location Information; separate definition of commercial mobile radio service.

“Enables real-time, two-way voice communications; requires a broadband connection from the user's location; requires internet protocol-compatible customer premises equipment; and permits users generally to receive calls that originate on the public switched telephone network and to terminate calls to the public switched telephone network.”

47 CFR 9.11: E911 service requirements for interconnected VoIP

Legal Information Institute, Cornell Law School

Independent Verified Sep 14, 2026 Supports: Fixed interconnected VoIP must provide automated dispatchable location with each 911 call from January 6, 2021, and non-fixed services from January 6, 2022, with Registered Location, alternative location information, or a national emergency call center as fallbacks; providers must advise subscribers

“On or after January 6, 2021, for fixed services, and on or after January 6, 2022, for non-fixed services... Providers of fixed interconnected VoIP services must provide automated dispatchable location with each 911 call.”

47 CFR § 9.16: General obligations for direct 911 dialing, notification, and dispatchable location

Legal Information Institute, Cornell Law School

Independent Verified Sep 14, 2026 Supports: Multi-line telephone systems must allow a user to dial 911 directly from any station with dialing facilities without a trunk-access code such as 9, and must be capable of providing the caller's dispatchable location to the answering point.

“a user may directly initiate a call to 911 from any station equipped with dialing facilities, without dialing any additional digit, code, prefix, or post-fix, including any trunk-access code such as the digit 9”

47 CFR 51.319(a), Specific unbundling requirements: local loops

Legal Information Institute, Cornell Law School

Independent Verified Sep 14, 2026 Supports: The local loop is the transmission facility between the distribution frame in the incumbent carrier's central office and the demarcation point at the customer premises, including the network interface device, which scopes the analog stretch of a copper line.

“The local loop network element is defined as a transmission facility between a distribution frame (or its equivalent) in an incumbent LEC central office and the loop demarcation point at an end-user customer premises.”

47 CFR 52.34, Obligations regarding local number porting to and from interconnected VoIP providers

Legal Information Institute, Cornell Law School

Independent Verified Sep 14, 2026 Supports: Interconnected VoIP providers must facilitate valid porting requests to or from carriers and other VoIP providers, may not contract around porting, and telecommunications carriers carry the matching obligation.

“An interconnected VoIP or VRS or IP Relay provider must facilitate an end-user customer's... valid number portability request... without unreasonable delay or unreasonable procedures.”

47 CFR 52.35, Porting intervals

Legal Information Institute, Cornell Law School (reproducing the Code of Federal Regulations)

Independent Verified Sep 14, 2026 Supports: A simple wireline-to-wireline or simple intermodal port must complete within one business day, and intermodal ports expressly include ports involving interconnected VoIP service.

“must complete a simple wireline-to-wireline or simple intermodal port request within one business day... The term 'intermodal ports' includes... Ports involving interconnected VoIP service.”

47 CFR 63.71, Procedures for discontinuance, reduction or impairment of service by domestic carriers

Legal Information Institute, Cornell Law School

Independent Verified Sep 14, 2026 Supports: A carrier seeking to discontinue, reduce, or impair service must notify all affected customers, the state public utility commission, the governor, affected federally recognized Tribal Nations, and the Secretary of Defense, and must obtain Commission authorization.

“The carrier shall notify all affected customers of the planned discontinuance, reduction, or impairment of service and shall notify and submit a copy of its application to the public utility commission and to the Governor of the State...”

47 CFR 9.20, Backup power obligations (2025 annual edition, since removed)

U.S. Government Publishing Office, GovInfo

Independent Verified Sep 14, 2026 Supports: Text of the repealed backup power rule: a Covered Service was any facilities-based, fixed residential voice service that is not line powered, and providers had to offer at the point of sale at least one option with a minimum of eight hours of standby backup power, plus a 24-hour option from February

“a Covered Service is any facilities-based, fixed voice service offered as residential service... that is not line powered... Providers shall offer for sale at least one option with a minimum of eight hours of standby backup power.”

Delete, Delete, Delete, Direct Final Rule, 91 FR 1400 (January 14, 2026)

Federal Communications Commission via GovInfo

Independent Verified Sep 14, 2026 Supports: 47 CFR 9.20 sunset by operation of law and ceased to be effective on September 1, 2025, and the FCC removed and reserved the section; the rule was published January 14, 2026 and effective March 16, 2026.

“One such rule provision, 47 CFR 9.20, has sunset by operation of law and ceased to be effective on September 1, 2025... Sec. 9.20 [Removed and Reserved]. Remove and reserve Sec. 9.20.”

Reducing Barriers to Network Improvements and Service Changes, Report and Order, 91 FR 20913 (April 20, 2026)

Federal Communications Commission via GovInfo

Independent Verified Sep 14, 2026 Supports: Copper retirement that also discontinues a service still requires section 214(a) authorization; direct notice of a planned copper retirement is 90 days before implementation, or 15 days where no customers are served; the Commission describes the legacy voice and 911 network as TDM-based infrastructu

“An incumbent LEC must provide direct notice of a planned copper retirement at least 90 days prior to implementation, except that it must provide direct notice of a planned copper retirement involving copper facilities not being used to provision services to any customers at least 15 days prior to implementation.”

Order, WC Docket No. 17-84 and GN Docket No. 13-5, DA 25-248 (March 20, 2025)

FCC Wireline Competition Bureau

Independent Verified Sep 14, 2026 Supports: The Bureau waived for two years the stand-alone service requirement and the requirement that a single replacement service satisfy all three prongs of the Adequate Replacement Test for legacy voice discontinuance applications, broadening eligibility for streamlined treatment.

“The Bureau waives this requirement for a period of two years... also waives for a period of two years the requirement that a single replacement service must satisfy all three prongs of the Adequate Replacement Test for legacy voice discontinuance applications.”

Results of the 2026 Urban Rate Survey for Fixed Voice and Broadband Services, DA 25-1088 (December 19, 2025)

FCC Wireline Competition Bureau and Office of Economics and Analytics

Independent Verified Sep 14, 2026 Supports: The 2026 urban average monthly rate for fixed residential voice is $33.99 and the reasonable comparability benchmark is $61.29; the average counts local end-user rates plus state-regulated fees and does not separate copper from IP-delivered service.

“Based on the survey results, the 2026 urban average monthly rate is $33.99. Therefore, the reasonable comparability benchmark for voice services, two standard deviations above the urban average, is $61.29.”

ITU-T G.711: Pulse code modulation (PCM) of voice frequencies

International Telecommunication Union (ITU-T)

Independent Verified Sep 14, 2026 Supports: The standard for digitizing voice frequencies used in carrier telephone networks was approved on November 25, 1988 and is still listed as in force, which dates the digital handling of a landline call beyond the central office.

“Recommendation G.711 (11/88). Approved in 1988-11-25. Status: In force.”

RFC 3261: SIP: Session Initiation Protocol

IETF

Independent Verified Sep 14, 2026 Supports: SIP is the application-layer signaling protocol that creates, modifies, and terminates sessions such as internet telephone calls, with media carried separately.

“an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls.”

AT&T Inc. Analyst and Investor Day transcript, December 3, 2024

AT&T Investor Relations

Supporting Verified Sep 14, 2026 Supports: AT&T's own statements: it will end 2029 exiting copper entirely; only 5% of its residential customers were still using copper voice technology; maintaining a fiber subscriber costs 35% less than a copper subscriber.

“We started this decade in 2020 with a pervasive copper footprint. We will end 2029 exiting copper entirely... only 5% of our residential customers are still using copper voice technology.”

AT&T Reports Fourth-Quarter and Full-Year 2025 Results (earnings release)

AT&T Investor Relations

Supporting Verified Sep 14, 2026 Supports: AT&T's own outlook language: the objective of powering down its energy-intensive copper-based network across the large majority of its footprint by the end of 2029, Legacy service revenue expected to be immaterial by the end of 2029, and the footnote that gaining approval of California regulators co

“its objective of powering-down its energy-intensive copper-based network across the large majority of its footprint by the end of 2029 and upgrading customers to advanced connectivity services powered by 5G and fiber... Gaining approval of California regulators could delay this decommissioning beyond 2029.”

Fios Digital Voice Battery Backup Unit

Verizon

Supporting Verified Sep 14, 2026 Supports: Verizon's own statement that a fully charged 12V battery provides up to 8 hours of backup power for voice services, including 911 calls, and that backup power does not support internet or TV service, which shows a fiber line marketed as home phone depends on local power.

“A fully charged 12V battery provides up to 8 hours of backup power for voice services, including 911 calls... Backup power does not support Internet or TV service during an outage.”

FCC Announces Compliance Dates for New E911 Rules Applicable to Multi-Line Telephone Systems and VoIP Providers

Wiley Rein LLP

Supporting Verified Sep 14, 2026 Supports: Law firm client alert dated December 3, 2020 recording the FCC's announcement of compliance dates under the 2019 Kari's Law and RAY BAUM'S Act order, including that the direct 911 dialing rules apply to MLTS manufactured, imported, offered for first sale or lease, first sold or leased, or installed

“Kari's Law and the FCC's rules on direct dialing and notification apply to MLTS manufactured, imported, offered for first sale or lease, first sold or leased, or installed after February 16, 2020.”

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