IP Trunking vs. SIP Trunking: What’s the Difference and Which is Best?

As cloud communication tools become the mainstream, businesses worldwide are exploring ways that cloud-based business phone service, fiber internet connectivity, and cloud backups can drive business value. Last year, an estimated 62 percent of businesses were using SIP trunking.

Understanding the advantages of IP-based phone service, and how they can be implemented at your business location is key to unlocking those advantages.

Two common terms that you may encounter when exploring IP and cloud-based phone service for the enterprise are SIP Trunking and IP Trunking. If you’re new to VoIP, you may be wondering what the difference is between IP vs. SIP trunking, and which is better.

Ultimately, there is no such thing as SIP Trunking vs. IP Trunking – they cannot be directly compared.

IP trunking is a term used to describe enterprise VoIP deployments, which may use SIP trunking or an alternative technology. While IP trunking and SIP trunking are both terms related to VoIP, they’re not the same thing, nor are they competing technologies.

IP Trunking vs. SIP Trunking: What’s the Difference?

IP trunking is large-scale VoIP deployments at organizations, including corporations or institutions. This term is relatively rare, and may be interchangeably used with “VoIP implementation,” or depending on the inclusion of multimedia features, “Unified Communications.”

IP trunking is different than plain old telephones (PoTs) services because voice transmissions are treated as data, and transmitted via data connectivity instead of analog phones, which transmit electrical-based signals through traditional telephone lines. IP trunking is also different than consumer VoIP products, including Skype and Vonage, which are generally not designed to meet the security and reliability needs of the enterprise.

IP trunking may be deployed at an enterprise in a number of ways, including an on-premises solution that is owned and managed by the organization, or a subscription to cloud-based VoIP service. It may also rely on either PBX trunks or SIP trunks. While a private branch exchange (PBX) is designed to support the transmission of voice as data, a SIP trunk can handle multimedia data, including voice, conferencing, emails, instant messaging, presence, and more.

IP Trunking vs. Alternatives

IP trunking, defined as enterprise deployments of VoIP, is not an alternative to SIP trunking. IP trunking is an alternative to publicly-switched telephone networks. Evaluating how IP trunking stacks up against alternative options requires comparing the solution to analog phones.

Pros of IP Trunking vs. Publicly-Switched Telephone Networks:

  • Lower Cost Savings
  • Superior Scalability
  • Can Include Sophisticated Multi-Media Communication Features
  • Can Quickly Add & Remove Phone Lies
  • Better Business Continuity & Lower Risk
  • Mobility

Cons of IP Trunking vs. Publicly-Switched Telephone Networks:

  • Requires Sufficient Data Connectivity for Quality of Service (QoS)
  • Desk Handsets May Not Working During Power Outages
  • May Not Operate Optimally with Public Internet Connectivity

The 6 Best Use Cases for IP Trunking

Organizations in all industries are driving value with VoIP. Highly-regulated firms are turning to Unified Communications as a Service (UCaaS) to diminish the administrative burden and skyrocketing costs of compliance. Educational institutions, like Montgomery College, are starting to realize that VoIP offers a pathway to next-generation, multi-campus connectivity.

While the following use cases are not a comprehensive representation of the full potential of IP Trunking, they’re worth noting:

  1. Reduce monthly phone bills by 20-30 percent or more
  2. Extend the life of legacy systems through hybrid VoIP-analog phones
  3. Improve employee productivity through mobility
  4. Increase information security
  5. Cloud adoption through implementation of Unified Communications as a Service (UCaaS)
  6. Reduce IT burden by outsourcing communication tools management via cloud VoIP or UCaaS


What is SIP Trunking?

SIP trunking is an abbreviation for session initiation protocol (SIP), a set of communications protocols that are a standard approach for managing the transmission of multimedia communications. SIP protocols are used to perform key actions necessary for placing and receiving calls, including establishing the call, terminating the call, and transmitting information. VoIP telephony supported by SIP trunking could either be hosted on-premises or in the cloud via a vendor partnership.

SIP trunking is not an alternative to IP trunking. It’s an alternative to PBX trunking or other methods of voice transmission such as Time Division Multiplexing (TDM) phones or publicly-switched telephone networks. For organizations who want to achieve the benefits of VoIP and make the transition to Unified Communications tools, SIP trunking is likely to be among the technologies used.

While IP trunking could be accomplished through a media gateway and PBX, an IP trunking implementation could involve SIP trunks and call routing through a session border controller (SBC). SBS is a complex piece of equipment that is used and maintained by VoIP vendors to act as a SIP application and perform other key actions, including access control, call accounting, and quality of service management.

Pros of SIP Trunking vs. Alternatives

  • SIP has the flexibility to support many media types
  • As an open standard, SIP can be used for integration with relative ease
  • SIP can simultaneously support multiple, multimedia data transmission

Cons of SIP Trunking vs. PBX Trunking

  • Skilled SIP trunking experts can be rare, which is why many organizations are choosing hosted IP trunking
  • Processing SMS messages places a higher load on SBCs
  • Not all SIP features are open standard

The 5 Best Use Cases for SIP Trunking:

  1. The potential for massive cost savings on scaling phone systems and adding lines compared to installing cabling for analog phones.
  2. SIP can support scaling without the need to purchase expensive additional equipment, unlike TDM phone systems.
  3. Ability to scale a single phone system across multiple business sites or support employee mobility.
  4. Save costs on long distance and international calling.
  5. Add support for Unified Communications, including collaboration tools like file sharing, desktop sharing, video conferencing, and more.

Wait, so is SIP Trunking or IP Trunking the Best?

SIP trunking is a technology used to power internet-based phone service and multi-media communications for businesses. SIP trunks are a component in many VoIP or IP trunking implementations, which replace the need for analog phone lines.SIP trunking can act as one form of support for business communications in an environment with VoIP or other unified communications tools, giving SIP trunking users the ability to select from a wide variety of multimedia cloud communication tools.

While VoIP is a well-established technology, the “right” way to drive value with VoIP and other Unified Communications tools ultimately depends on your businesses’ requirements, budget, and goals. If your organization wants to work more collaboratively, streamline your communications technology and save costs, you’re likely a good candidate for VoIP phone service. However, the exact features you should deploy ad the right approach to implementation can vary.

While SIP trunking and IP trunking are both terms from the VoIP ecosystem, they’re not quite the same thing or alternatives to each other. Organizations who want to move their communications tools to the cloud should consider all of their options, including SIP trunking, and select the method that is most beneficial.


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