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Five Factors to Consider When Choosing a SIP Trunk Provider

As businesses continue to modernize their infrastructures, cloud telephony solutions are quickly gaining popularity. For example, SIP trunking is a solution that helps companies eliminate physical phone lines by using virtual channels, which is a more cost-effective and scalable alternative to older analog solutions.

In this post, we’ll look at what SIP trunks are and the most important considerations when choosing a SIP trunk provider. Let’s dive in.

What is SIP Trunking?

The session initiation protocol (SIP) is used to initiate, manage, and terminate connections for real-time calling and messaging at the application level. SIP trunking links a company’s telephony infrastructure to the public phone network over the Internet using the SIP standard.

More specifically, a SIP trunk is a virtual version of an analog phone line that enables a private branch exchange (PBX) to communicate with the public switched telephone network (PSTN). In the past, an analog “trunk” was a collection of copper wires that ran from a specific business location to the local phone company. A SIP trunk, however, is a service that consists of multiple channels that enable SIP-based communication such as voice and video calls, instant messaging, multimedia conferencing, and more.

Many companies are using SIP trunks to replace physical ISDN circuits—the copper lines installed on-premises—with a virtual solution. Primary Rate Interfaces (PRIs) were the most popular standard used on the outdated ISDN system, but scalability was limited because each circuit only allows up to 23 concurrent calls. Since SIP is an internet communications protocol rather than an analog voice technology based on physical lines, it’s a more flexible and scalable solution for modern businesses.

SIP Trunks for Microsoft Teams

As part of their telephony modernization efforts, many organizations are choosing to use Microsoft Teams as a complete communications solution. Direct Routing is a way to connect Microsoft Phone System, a hosted PBX solution, with the PSTN network. In this case, managed service providers offer SIP trunking as part of an end-to-end cloud telephony solution. That means companies can use Microsoft Teams as an enterprise-grade unified communications (UC) platform.

Moreover, Microsoft recently announced support for most SIP phones. In the past, Microsoft Teams was only compatible with Microsoft-certified devices, but now SIP phones and headsets from major manufacturers like Cisco, Yealink, and Polycom can be used with the platform. This has opened the door for more enterprises to leverage Microsoft Teams as their primary telephony solution.

What Are SIP Trunking Providers?

A SIP trunking provider is a company that offers digital communications services like SIP trunking to businesses that want to connect their internal PBX system to the external PSTN network. As mentioned, some cloud telephony providers also offer SIP trunking and Microsoft Teams Direct Routing as complete end-to-end managed services.

SIP trunking providers usually use a session border controller (SBC) to control communication between the SIP trunk and the company’s phone system An SBC ensures secure and reliable data transfers between two separate networks while also optimizing the flow of traffic for improved voice call quality.

Along with SIP trunking providers, companies do have the option to implement their own SIP trunk. That said, installing and managing a SIP trunk requires specialized telecommunication knowledge that most companies won’t have available in-house. For most businesses, building a custom SIP isn’t recommended because it’s not a core competency and is usually cost-prohibitive.

Choosing a SIP Trunk Provider

When it comes to modernizing your telephony infrastructure, there are numerous service providers to choose from. Here are five factors to consider when selecting a SIP trunk or managed service provider.

  1. Call Volume
  2. A SIP trunk is typically a set of channels, with each channel capable of handling one incoming and one outgoing call at the same time. That means it’s important to understand how many simultaneous calls your infrastructure will need to support so that you can choose the right number of channels.

    Most managed providers can help you estimate call capacity requirements during the implementation. That said, it’s much easier to scale the number of channels up with cloud-based SIP trunks than it was with on-premises PRI solutions, so SIP trunking is a much more elastic telephony solution.

  3. DID Numbers
  4. SIP trunks are usually assigned a range of Direct Inward Dialing (DID) numbers, which forwards incoming calls to specific SIP phones. Most managed providers can also help port existing DID phone numbers over to their new telephony infrastructure so that employees are unaffected by the migration.

    While you may be able to port your existing numbers, there are some situations where they can’t be ported, such as a lack of an interconnection agreement between carriers or service has already been cancelled and the number has been assigned to a new customer. In these cases, you’ll need to purchase new DID numbers. Since SIP trunks don’t require installing physical lines, DID numbers are cheaper and more convenient to purchase.

  5. Reliability
  6. When it comes to voice communication, reliability is crucial for achieving a high Quality of Service (QoS). Voice signals can require a lot of data, so compression is used to reduce the amount of bandwidth necessary for transmission without negatively impacting quality. It’s important to choose a provider that supports a modern and efficient codec like G.711 or G.729 to optimize QoS and bandwidth.

    It’s also crucial to choose a provider that can connect your PBX to a reliable network with tier-1 carriers, which are carriers that can route calls to nearly any other network without additional charges. This network should include redundant carriers for each region you operate so that calls can be rerouted to bypass trouble spots during outages or other issues as well. This will ensure that your telephony infrastructure maximizes uptime and availability.

  7. Pricing
  8. SIP trunking is usually priced per user, per minute, or as part of a larger service fee that includes direct routing, an SBC, and other telephony infrastructure. A managed service provider can offer an end-to-end solution so that you don’t need to deal with the expense of installing and maintaining telephony hardware.

    In addition, many managed providers offer their own global networks that leverage local PSTN carriers, which can lead to lower costs due to economies of scale. You won’t need to form vendor relationships with multiple local carriers yourself or use multiple Microsoft Calling Plans for different regions. That means SIP trunking, as part of a cloud telephony solution, can have a lower total cost of ownership when compared to on-premises alternatives.

  9. Security & Privacy
  10. SIP trunks exist outside the organization’s network, so it’s crucial to ensure the service provider you choose follows security and privacy best practices. For example, using an SBC can improve security by analyzing traffic and only allowing incoming traffic that’s from a device whitelisted within an access control list (ACL). The SIP trunk should also only accept incoming traffic from your managed provider’s SBC for an additional layer of security.

    Besides security, many businesses operate in industries that have strict data privacy regulations and need to ensure their communications are only accessible by authorized users. For meeting privacy standards, you should consider a managed provider that encrypts SIP traffic using the secure real-time protocol (SRTP) and transport layer security (TLS).

Modernize Your Telephony Infrastructure

Using software-based solutions for your business communications infrastructure can lead to greater reliability and significant cost savings. Moreover, a Microsoft Teams Direct Routing solution atop a SIP trunk and SBC can enable companies to streamline their cloud telephony infrastructure by leveraging a single platform for company-wide communications and collaboration. 

Microsoft Teams is the chosen platform for many enterprises because it gives their workforce the flexibility to communicate whenever and wherever they want. Employees can make and receive phone calls on desktops, laptops, smartphones, and Teams-enabled desk phones or headsets. This ensures seamless company-wide communication using a centralized cloud telephony solution.

LoopUp is a managed service provider and certified Microsoft Gold Partner that implements Microsoft Teams Direct Routing for unified communications. The company helps its customers every step of the way, from porting DID numbers to implementing SBCs and SIP trunks. With 15 offices around the world, LoopUp also offers 24/7 multilingual support should any issues arise.

With its own highly reliable private global network that leverages 14 carefully-selected tier-one carriers and regional carrier redundancy, LoopUp achieves 99.995% uptime availability. All routings also use perceptual evaluation of speech quality (PESQ) to determine their quality.

Besides service quality and reliability, LoopUp also puts a priority on privacy and security. In fact, the company is ISO 27001 accredited globally, which means the company has the processes in place to protect sensitive data. For these reasons, over 5000 enterprises worldwide have chosen LoopUp as a trusted partner to help modernize their telephony infrastructure.

Want to learn more about modernizing your telephony infrastructure? Contact LoopUp to discuss how we can support your cloud communication journey.

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