GUIDE FOR BUSINESSES · OCTOBER 2026

How to choose a PBX for your company

Before comparing equipment or monthly fees, define how your company handles calls. This list helps you request comparable proposals and identify what to confirm before signing.

1. Count users and calls separately

An extension identifies a user or a desk; simultaneous calls indicate how many conversations you need to hold at the same time. They are different quantities. A company with many employees may need fewer simultaneous calls, while a reception desk may handle several calls at once.

• How many people need an extension today, and how many might need one later?
• How many incoming and outgoing calls overlap during the busiest hour?
• Does your company have a reception desk, departments, several sites or staff who work outside the office?
• Which current numbers and equipment do you want to keep?

2. Compare an on-premises PBX with a hosted service

A PBX manages and routes an organization’s calls. An IP PBX uses the data network and can work with IP phones and telephony applications. Compatibility depends on the system and the devices. Cisco explains these differences in its introduction to PBXs.

Ask for each proposal to state where the PBX is hosted, who manages it, which equipment stays in your office and what happens if the connection is interrupted. To compare an on-premises installation with a hosted service, ask separately about equipment purchase or rental, licenses, maintenance, connectivity and recurring charges. Do not assume one model includes all the features of the other.

3. Review the network and the power

Voice over IP needs a network that carries conversations with good quality. Bandwidth matters, but so do delay, delay variation and packet loss. Prioritizing voice traffic can help when there is congestion; it does not replace an adequate connection. See Cisco’s technical explanation of QoS and VoIP.

Before switching PBXs, ask who will review the internet connection, the switches, the network points and the power for the phones. Ask the provider to explain the backup options and their limits. Backup power in the office does not, by itself, guarantee that the internet service or the hosted PBX will stay available.

4. Write down the path of a call

Run a test on paper: someone calls the main number, hears the options, chooses a department and nobody answers. Should the call go to reception, to another group, to a voicemail box or to a recorded message? Repeat the exercise outside business hours. That description is more useful than a list of features without context.

• What options does the call menu or IVR need?
• Who receives each type of call?
• What happens when the lines are busy or nobody answers?
• Do you need reports or recording? Confirm availability, storage, access and terms of use.

5. Request a proposal that helps you make a decision

Ask for quantities, models, contracted features, installation, configuration, training and support in writing. Separate initial costs from recurring ones and ask what generates additional charges. Confirm with the provider the availability or transfer of numbers, the cancellation terms and the procedure for changing solutions later.

Before accepting delivery, agree on tests for incoming and outgoing calls, transfers and call-handling paths. Define who will approve the result, who will manage users and which channel you will use to ask for help. Hours, response times and exclusions should be written into the agreement.

Information for requesting your proposal

Have details ready on your city, sites, users, estimated simultaneous calls, current numbers, equipment and desired call-handling path. TESERCOM assesses on-premises or virtual PBXs according to the operation; equipment, features and conditions are confirmed in the proposal.

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This guide offers general purchasing criteria. The assessment of your infrastructure determines the applicable scope.