SIP Trunking Service

What Is SIP Trunking? And Why Is It Important For Your Business?

Small and large businesses are searching for ways to make their marketing and communication campaigns more effective. This feat is complicated as many companies seek to make digital connections. Many companies are flocking to SMS and email campaigns with good reason, but many need to pay more attention to the power of SIP trunking as a viable communication medium.

SIP trunking allows businesses to consolidate voice communications and more effectively reach customers using the Internet. It works well with other communication and marketing methods, especially voice broadcasting, making it an even more attractive option for businesses. Please keep reading to learn more about SIP trunking, its costs, and how your company can get started using it.

What Is SIP Trunking?

The ‘SIP’ in SIP trunking stands for ‘Session Initiation Protocol.’ Session Internet Protocol refers to businesses using the Internet to communicate (i.e., as a communication channel). SIP trunking is when businesses consolidate multiple SIP sessions, using the Internet to send out mass communication.

How Does SIP Trunking Work?

These SIP trunks work like virtual phone lines, allowing businesses to connect with customers worldwide using the Internet. This means that you don’t need phone lines to send and receive calls or voicemails; the Internet takes the place of these networks.

SIP trunks connect multiple channels to a PBX, ‘Private Branch Exchange.’ A PBX is essentially a private telephone network that connects users. For businesses, a PBX can control and operate its internal telephone network. So here’s how that works: multiple calls come into your business (or your business sends out multiple calls). These calls are routed through your company’s PBX, which then interacts with the SIP station. These calls are bundled into SIP trunks, then sent out via the Internet.

Using SIP trunks, your business can send out calls locally or internationally to hundreds or thousands of customers within seconds. SIP trunking offers several benefits, including reliability, scalability, and cost savings. There are also fewer maintenance costs since your business is leveraging the existing power of the Internet through a SIP service.

What Is A SIP Provider?

SIP providers are software companies that offer businesses the ability to integrate SIP trunking into their marketing and communication campaigns, typically as an optional feature through an existing software or API. So, a service provider may offer voice broadcasting software for your business to utilize a SIP trunking feature.

Your business can also look into an exclusive SIP provider. Still, looking for providers with various communication and marketing options that can be integrated and used across your channels (i.e., SMS messaging, emails, voicemails, calls, etc.) is more economical.

By investing in a provider that offers multiple communication options versus just SIP trunking, your business can leverage the collective benefits while maximizing savings.

An example would be signing up with a provider offering voicemail broadcasting with SIP trunking and phone verification services to ensure the phone numbers you use are valid and active. Without the verification services, even if your SIP trunking worked correctly, its success would still be limited.

SIP trunk providers vary widely, as with any other software provider. Your business should carefully research available providers to see which will meet your needs best. This includes comparing pricing, additional features, and software demos in real-time. It would help if you also looked into free trials or credits so your company can compare and contrast how they work.

How Much Does SIP Trunking Cost?

Searching for SIP trunking services would be ideal for businesses with free SIP trunks. But while you won’t find free trunking with a reputable business, you can find cost-effective trunking. Two direct costs are associated with SIP trunking: the set-up fee and the monthly cost per trunk.

Costs vary depending on your SIP telecom service provider, so ask about them upfront before signing up or agreeing to any contracts. For providers where SIP trunking is included, ask if the price is rolled into the software itself (such as voice broadcasting) or incurs separate costs.

Your business should also inquire about ways to save money, such as traction-based pricing, volume discounts, etc. Feel free to ask for price-match guarantees, if appropriate, or about custom quotes based on your needs. If your business communicates internationally, you should also ask about international capabilities (what countries you can connect with), international pricing, and how it affects your billing.

How Many Calls Can You Make With SIP Trunking?

The number of calls your business will be able to make with SIP trunking will depend on the bandwidth capacity of your service provider. Remember that SIP trunking relies on the Internet, so your upload speeds will likely be slower than your download speeds.

As a result, when inquiring about the bandwidth and supported calls, you should ask about upload speeds. This will prevent any unpleasant surprises in the future. But your business would like to manually calculate the number of calls you can make. In that case, there is an equation you can use: (number of concurrent calls during your busiest hours) x (100 Kilobits/second) = (bandwidth in megabits per second).

This equation can get tricky, especially if you don’t know the number of concurrent calls you get during specific business hours. Even so, it doesn’t hurt to have the means to calculate this yourself if you don’t want to or can’t ask potential service providers (or want to confirm their answers).

SIP vs. VoIP: What To Know

SIP and VoIP are two related tools but are still distinctly separate. While SIP is the protocol to consolidate and manage mass voice calling, VoIP transfers data over the Internet. SIP and VoIP technically power voice, video, and text messaging.

VoIP stands for ‘Voice Over Internet Protocol.’ VoIP converts voice messages into digital signals that can travel over the Internet. These signals are directed by (you guessed it) SIP links and can be consolidated using SIP trunking.

However, businesses should be careful when using SIP and VoIP. Remember that both of these services are Internet-dependent, which means you lose your communication ability if you lose power. Recognizing this, you should ask potential providers how they can guarantee continued power and what will happen during emergencies.

How Can Esendex Help Your Business?

Esendex’s Phone Notify! API is a voice broadcast service that allows businesses to easily automate and send mass calls to customers, connecting with thousands of users in seconds. SIP trunking is just one of the many features that Phone Notify! Offers. Other features include interactive voice responseanswering machine detectiontext-to-voice, multichannel communication, and real-time reports.

With our API, businesses can send up to 12,000 messages per minute using our Tier 1 SMS network backed by our 99.9% uptime guarantee (outlined in our SLA) and 24/7 emergency support (available via live chat, Phone, and email).

Besides being satisfied with our features and service, customers are also pleased with our pricing options. We offer pay-per-transaction pricing (so that you only pay for what you use), volume-based discounts, price-match guarantees, competitive international pricing, and custom quotas. These are just some reasons that Esendex is rated 5 out of 5 stars on Google, Facebook, Capterra, and GetApp—interested in learning more? Schedule a meeting to ask about how we can help boost your business using voice broadcasting and SIP trunking.

Products for a range of use cases


Texting API designed to send & receive SMS & MMS globally using a short code or 10DLC number.

SMS Software

Easy to use SMS software that can send & receive SMS & MMS using a short code or 10DLC number.

Voice Broadcast

Powerful voice API that sends mass automated phone calls quickly to mobile & landline devices.

Phone Verification

Verify mobile & landline numbers, find service providers, & define time zones to restrict calling.

Let’s start sending, together.