VoIP and IP-PBX basics for offices

An IP-PBX replaces the old key telephone system with a server that routes calls over the office network and the internet. This guide explains the parts of a VoIP system, the trunk options available in Malaysia, what to check on the network, and how the Yealink and Yeastar products on this site fit together.

What this guide covers

IP-PBX servers, SIP phones, softphones and gateways
Trunks: SIP trunks from a provider, analog lines through an FXO gateway, GSM gateways
Features: auto attendant, queues, voicemail, call recording, remote extensions
Network requirements: PoE, VLAN and QoS for voice
Migrating from an analog PABX without replacing every phone
Headsets, conference phones and DECT handsets

Typical applications

Offices with 10 to 500 extensions
Clinics, schools and hotels
Companies with branches or home-based staff
Customer service desks

What you will find

Plain explanation of SIP, codecs and registration
Checklist for a reliable voice network
Trunk choice by cost structure and reliability needs
How to keep existing analog phones and fax through gateways

Functions vary by model and firmware; see each model page and the official datasheet.

Selection questions

How many extensions and concurrent calls?
Which trunks does the company have or plan to have?
Do staff work remotely or across branches?
Is the network ready: PoE switches, VLAN for voice?

Prepare an enquiry

ISD in Kuching, Sarawak handles IP-PBX enquiries for projects in Sarawak and Malaysia. Send the full model code and quantity, or describe the site. Supply only; ISD confirms the model separately.

Describe your requirement

Frequently asked questions

What is a SIP trunk?

A connection from a telephony provider that carries calls over the internet to the IP-PBX, replacing physical phone lines.

Can we keep our analog phones?

Yes. An FXS gateway such as the Yeastar TA series connects analog phones and fax machines to the IP-PBX.

Which VoIP products does ISD list?

Yeastar P-Series and S-Series PBX, Yeastar TA and TG gateways, and Yealink desk, conference and DECT phones; see the linked guides.

VoIP and IP-PBX basics for offices - models on this site

20 more related models are listed in the product catalogue.

Related guides and categories

Reference

Written by ISD from manufacturers' public product information; confirm specifications on each model page and the official datasheet. Checked 2026-11-01.