--- title: "Enterprise SIP Trunk – Complete Guide, Part 1" id: "231" type: "post" slug: "enterprise-sip-trunk-complete-guide" published_at: "2018-01-17T14:55:19+00:00" modified_at: "2025-12-08T18:56:02+00:00" url: "https://www.simpletech.uy/en/troncal-sip-empresarial-guia-completa/" markdown_url: "https://www.simpletech.uy/en/troncal-sip-empresarial-guia-completa.md" excerpt: "Corporate telephony has had to incorporate new features to adapt to market needs. This guide explains what SIP trunks are, their advantages, and how to migrate." taxonomy_category: - "Communications" taxonomy_post_tag: - "Unified Communications" - "IP PBX" - "IP Telephony" - "SIP Trunk" --- As we discussed in previous posts, corporate telephony has had to incorporate new functionalities for years to adapt to market needs. This is why the natural evolution of the TDM world led to IP. The old and reliable PSTN (Public Switched Telephone Network)—with its analog lines, ISDN BRI, E1, or T1—is about to disappear. Telephony is shifting from the PSTN to much more modern and flexible SIP (Session Initiation Protocol) trunks. A few years ago, all communications were carried out using circuit switches on the public telephone network and within companies. This approach became inefficient with the growth of data networks, the rise of smart devices, and the need to integrate applications with telephony. Major telecommunications providers are rapidly phasing out legacy PSTN functionality and migrating customers to IP. Therefore, a SIP trunk and a telephone exchange upgrade will be inevitable in the near future. **To use the SIP Trunk service, your company needs an IP telephone exchange (IP PBX).****Verizon** has stopped offering basic ISDN services to its customers in the United States. In the United Kingdom, the number of ISDN lines has dropped to 3 million from 4.7 million in 2007, and the decline is accelerating. In 2017, major telephone operators such as **BT, KPN, France Telecom, Deutsche Telekom, and Telecom Italia** will no longer offer ISDN lines. As a result, demand for **SIP trunks** increased by 62% in 2015 compared to the previous year. This guide explains what SIP trunks are, their advantages, and how to migrate. **Calls within the NGN network** SIP trunks enable end-to-end IP calling, allowing business communications to be dynamic, efficient, and established virtually seamlessly. SIP trunks are fully compatible with the PSTN network. Incoming and outgoing calls can be established seamlessly with this network. **What Are SIP Trunks?** SIP trunks are telephone lines that operate over IP using the SIP protocol. Using this standard protocol, telecommunications service providers (VoIP) connect one or more channels to the customer’s PBX. Telephone numbers and DIDs are linked to the SIP trunk. **Benefits of SIP Trunks** Making voice calls over IP—using SIP standards for signaling and RTP for media—provides greater communication flexibility for businesses, enabling new multimedia service possibilities and many benefits. SIP trunks offer: **Lower monthly fees for lines and DIDs** The monthly cost of having multiple lines installed in your office is significantly reduced with SIP trunks. Similarly, DIDs cost much less (in most cases). **Voice quality** Excellent voice quality on calls. **Better Customer Service** Provide better service to your customers by adding more local and international numbers. Simply adding numbers to your SIP trunk and routing them to your IP PBX will give your customers more options to reach you, at a significantly lower cost. **Reduce barriers to contact and increase sales.****Branches easily connected** For customers with multiple branches, it is possible to design a solution where only the central site has a connection to the telephone network and the rest of the branches can use lines from this site. **Move your offices and keep the same number** SIP trunks are not tied to a physical location, so it’s very easy to move offices without having to change your business cards or inform your clients of new numbers. You don’t need to go through the hassle of paying the carrier to redirect phone calls. **Eliminate costly gateways and interfaces** Customers with IP PBX systems do not need gateways to connect to the PSTN network. All phone calls are transmitted over IP. This results in better call quality by avoiding additional audio conversion. The customer does not need to install expensive interfaces (e.g., E1 cards). **Flexibility** Greater flexibility in setting the number of simultaneous calls, unlike E1 lines, which have a fixed number of channels. The number of simultaneous SIP trunk sessions can be increased without the need for any additional installation at the customer’s site or the installation of another service. Keep in mind that for analog telephones, a copper pair must be installed for each line, and for digital telephony, another E1 line must be installed. **Correct number of channels** The SIP trunk can be made independent of the access medium used to reach the customer’s site. This **allows the company to provide the number of voice channels it needs** by choosing the most suitable access technology for each situation. With SIP trunks, you can easily select the exact number of channels you need, whereas with ISDN/T1, you often had to choose between adding 15 or 30 lines. This usually means that **you end up with expensive, unnecessary extra capacity.** It’s very easy to add more channels to your SIP trunk to handle increased call volumes. A simple phone call is all it takes to add channels, and this can often be done instantly. Compare that to having to hire contractors to install additional lines in your office—and then having to upgrade your old PBX to handle more lines! **Easy Maintenance** Maintenance is easier compared to conventional telephone systems because the setup is simpler. **Take Advantage of a Modern IP PBX** Modern IP PBX and Unified Communications solutions provide businesses with increased productivity, mobility, and better results. Connecting an IP PBX to a SIP trunk is much easier than connecting through the PSTN. **Things to Consider**- Security: It is very important that the SIP trunk and IP-PBX have a well-secured network and an anti-fraud system in place. The anti-fraud system should monitor the system and provide protection against fraudulent calls. - Own network: Does the SIP trunk provider have its own network, or is it a rebrand of a third-party service? There are a few providers that resell SIP trunks from other providers. Choose a provider that has control over both the service and the network. - Competitive Costs: Costs can vary widely from one service to another. Some providers charge more for SIP trunks. Shop around for competitive rates, but make sure you’re getting business-grade SIP trunk services. - Number Portability: Can the provider port your phone numbers? Make sure you choose a provider that can port all your existing numbers—not all providers can do this in all regions. **Upgrading Your PBX to an IP PBX** Most likely, your old PSTN lines are connected to another outdated device: the telephone switchboard. This device is inflexible, difficult to manage, and often expensive. Technically, it is possible to purchase a gateway that allows the old PBX to communicate with the SIP trunk. But why not upgrade to a modern IP PBX and take advantage of the flexibility and modern features that IP telephony has to offer? There are many reasons to do so, ranging from cost savings and productivity gains to the large-scale Unified Communications capabilities that an IP PBX provides. You can choose between a hosted PBX, a dedicated server, or a virtual machine on which to install your PBX. _____________________________________ Looking for **advice** on setting up a SIP trunk for your company? Talk to an expert. At [SimpleTECH](https://www.simpletech.uy/en/index.html/) We can help you. We have the specialized knowledge needed to ensure the transition process runs completely smoothly and without issues. Contact us. We are the only Spanish-speaking Platinum and Support Partner of 3CX in Latin America. 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