SIP vs. VoIP: Understanding the Differences

VoIP and SIP are two of today’s most important communications technologies. They share some important similarities, both representing Internet-based alternatives to traditional telephonic communication. But they are also distinguished by some important differences. Most notably, VoIP is a voice-oriented technology, while SIP is a multimedia communications tool. Additionally, there are several other significant differences between these two technologies.

Understanding the difference between SIP vs. VoIP can help you understand which one is the best choice for your business and which communications provider can best need your communications needs. Here’s a look at SIP vs. VoIP phone services, how they compare, how they differ, and how to choose which one is right for you.

VoIP: Talking over the Internet

Voice over Internet Protocol (VoIP) is a technology that allows users to make phone calls over the Internet instead of using traditional telephone lines (known as Public Switched Telephone Network, or PSTN). VoIP also goes by a number of other names, including:

  • Voice over broadband
  • Broadband phone service
  • Broadband Telephony
  • Internet telephony
  • IP telephony
  • IP communications

VoIP can be used to send or receive voice messages over the Internet or a company’s internal network. Some VoIP services only allow you to call someone else who uses the same service, while others allow you to call anyone who has a phone number, including local, long distance, and international numbers as well as mobile numbers. When you use VoIP to call a regular phone number, the signal transmitted over the Internet gets converted into a regular phone signal before reaching its destination. Some VoIP services may not allow you to call 911 or directory assistance.

You can place a VoIP call from a computer, a special VoIP phone, a regular phone with an adapter, or a wireless hot spot such as a café or airport. Some VoIP services may not work during power outages.

One of the main attractions of VoIP is its affordability. Because VoIP calls are transmitted over the Internet, VoIP is much more affordable than traditional phone calls.

SIP: Holding Multimedia Conversations over the Internet

Session Initiation Protocol (SIP) is a system of coding rules used to initiate, carry on, and terminate real-time communications over the Internet using voice, video, or instant messaging. A SIP session can connect two participants or more than two participants. The SIP protocol is encoded in a text-based language similar to the HTTP protocol used for transferring website files over the Internet and the SMTP protocol used for sending emails. SIP coding describes the identity of participants in a call and how these participants can be reached over an IP network.

SIP sessions can be initiated over computers or special phones. SIP phones use a modem to connect to the Internet.

How SIP vs. VoIP Phone Services Compare

VoIP and SIP share in common their use of the Internet to transmit communications. However, they are also distinguished by some fundamental differences:

  • VoIP is exclusively for voice communications, while SIP is a unified communications protocol that can handle voice, video, or instant messaging communications, making SIP preferable for companies with remote workers where multimedia presence is desired
  • SIP signals can be integrated with other protocols, allowing SIP transmissions to be adapted to use by other protocols and affording more flexible scaling
  • SIP is a formal signaling protocol, whereas VoIP is an informal term for a collection of similar technologies
  • VoIP phones rely on a connection to a computer, while SIP phones do not
  • VoIP hosting services route signals through a central network, which can tax systems when call volume grows too large, while SIP systems are processed using resources on each user’s system, allowing for greater bandwidth use and higher call volume
  • VoIP is less complicated to install than SIP, making SIP more suitable for companies with strong IT support
  • In general, these distinctions make VoIP more suitable for situations requiring one-on-one voice conversations, while SIP is more suitable for communications over multiple media involving multiple parties. SIP is also more suitable for companies that require multimedia conversations with remote workers.


VoIP is geared towards voice communications between single parties, while SIP can support multimedia conversations between multiple parties. Whether you choose VoIP or SIP, the key to reliable communication lies in choosing the right provider. When it comes to VoIP, 8x8 provides a reliable and compliant cloud solution at a demanding level rarely seen by other cloud providers. Don't take your chances with a subpar cloud-based telecom system. Call 1-866-879-8647 or fill out an online form to request a no-obligation quote from an 8x8 product specialist.

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