ESI 50 and 100 Business Phone Systems

The ESI-50 & ESI-100 Communications Server is a powerful tool around which you can build your organization’s entire telecommunications strategy — and you don’t have to know it all in advance.

That’s because the ESI-50 & ESI-100 can be a traditional digital business phone system, a fully standards-based IP telephony system, or any mix of the two. The choice is entirely yours, and the mix can easily change when your needs do.1



Commercial Telephone Systems is certified in ESI Communication Systems and are able to provide phone maintenance. Progressive vision, leading-edge technology, legendary reliability, and outstanding products define ESI. Since its inception in 1987, ESI — a privately held corporation based in Plano, Texas — has enjoyed growth and uninterrupted profitability. ESI designs and manufactures high-efficiency, low-cost business communications products. These products have earned numerous product awards from industry publications.


ESI was the first company to build a truly combined telephone and voice mail system, as well as the first to build a purely IP-based business communications system, and has numerous patents granted or pending on its products’ unique designs and capabilities. ESI is highly regarded for supporting unique, real-world applications with practical and effective features. How does ESI accomplish these feats? By using digital signal processors (DSPs) — high-powered semiconductors that manage analog functions in a digital environment — and ESI’s innovative system software to replace hundreds of hardware components. This enhances product reliability. It also makes the design and production of new systems, as well as the upgrading of existing systems, more efficient and cost-effective.


Customer-focused product development
— ESI consistently incorporates the newest advanced and viable technologies into usable, real-world products and enhances them based on feedback from real-world customers like you.

Commitment to total customer satisfaction
— ESI understands the needs of real-world businesses like yours, and designs systems with you in mind. That’s why ESI consistently earns praise for exceeding expectations.

Financial stability and strength
— ESI has been self-funded and profitable since its inception, through good times and bad. Effective management of the company’s growth and sound fiscal policies are the guiding principles of the ESI management team. Businesses are searching for products designed to meet their specific needs. ESI telecommunication products meet that criterion and are significantly easier to use than their competitors. ESI combines today’s products with a clear vision of the future. ESI and its nationwide network of ESI Certified Resellers are prepared to grow with you now and for many years to come.

Commercial Telephone Systems is a proud vendor for ESI Phones located in the St Louis, Missouri and Illinois Locations.

ESI 50 Communications Server

Ideal for small and growing businesses, Basic Edition provides basic voice telephony and messaging, including voice mail, message to email conversion, call forwarding, audio conferencing, automated attendant and growth to 100 users.

ESI 100 Communications Server

Builds on the Basic Edition by adding IP telephony and mobility features, including one-number access and dial by name / extension. Scales to over 350 users.