An IP PBX carries calls over the computer network, bringing flexibility, remote working and reporting. Learn how it differs from a traditional PBX and what to watch for in network, power and security.
A phone system, or PBX, connects the phones in your business to each other and to outside lines, and routes incoming calls to the right person. For many years these systems ran on a box on the wall and copper cabling; in most businesses today they are being replaced by IP PBXs that run over the computer network. The change is not only technical: it also affects the cost structure, maintenance habits and what you need from your network.
How does a traditional PBX work?
A traditional PBX is a physical device fitted with line and extension cards. Each desk phone connects to it with its own cable, and outside lines come in from the operator as analogue or digital lines. Adding a new extension often requires a free port, possibly a new card and a new cable run.
The strength of this setup is its simplicity: once installed, it can run for years with little intervention and is unaffected by problems on the computer network. Its weakness is limited flexibility. Internal calls between branches, a remote employee making calls from their office number, or detailed call reports are either unavailable or need extra hardware. Finding spare parts for an old PBX that the manufacturer no longer supports can also become difficult.
What is an IP PBX?
An IP PBX carries voice calls by converting them into the same data packets used by the internet and your local network. This technology is generally called VoIP (voice over internet protocol). The PBX itself is software: it can run on a server or a small appliance in your office, or be used as a cloud PBX hosted on a service provider's infrastructure.
Extensions can take three forms: IP desk phones connected with a network cable, software phones (softphones) running on a computer, and apps installed on mobile phones. Outside lines usually arrive as virtual lines called SIP trunks, delivered over the internet or a dedicated data line. SIP is a widely used protocol for setting up and ending IP-based calls. If you want to keep your existing analogue or digital lines, gateway devices can connect them to the IP PBX.
Comparison
| Topic | Traditional PBX | IP PBX |
|---|---|---|
| Infrastructure | A separate phone cable for each handset | The computer network; phone and computer can share one cable |
| Adding extensions | May need a free port, a card and new cabling | Usually configured in software |
| Remote work and branches | Limited, needs extra hardware | An office extension can be used via an app or a network connection |
| Features | Basic routing, hold, transfer | Voice menus, call recording, reporting, integration with business applications |
| Dependencies | The PBX and phone lines | Local network, internet connection and power |
| Security risk | Mostly limited to physical access | Exposed to network-based attacks, needs regular updates |
| Cost structure | High upfront investment, little change | Installation, per-user licences or a monthly service fee |
What an IP PBX brings
Flexibility
When an employee moves desks, they simply plug their phone in at the new spot and their extension goes with them. A new starter can be given an extension without running any cable. A remote employee or a salesperson in the field can call from the office number and take calls on it through an app on their mobile phone.
One system across branches
In businesses with several locations, all branches can connect to a single PBX. Calls between branches use extension numbers, and customers can dial one number and be routed to the right department.
Measurable service
Information such as how many calls go unanswered, how long customers wait and which hours are busiest can be reported. Features such as voice menus, out-of-hours routing and call queues make customer communication more orderly.
Points to watch
Network quality determines call quality
With an IP PBX, voice travels over the same network as other data. Packets that are delayed, arrive unevenly or get lost are heard as choppy, echoing or robotic audio. To prevent this, a common practice is to put voice traffic on a separate virtual network (VLAN) and give it priority on network devices (QoS). Assess your internet line's upload capacity as well as its download speed; the need grows with the number of simultaneous calls. Calls made over Wi-Fi are more easily affected than those over a wired connection.
Power and connection outages
IP phones usually draw power through the network cable, which requires a switch that supports PoE (Power over Ethernet). For phones to keep working during a power cut, the switches, modem and firewall need to be on an uninterruptible power supply (UPS) along with the PBX. If the internet goes down, outside calls may stop too, so a fallback plan, such as automatically forwarding calls to a mobile phone, should be prepared in advance.
Security
An IP PBX exposed to the internet attracts attackers. The best-known risk is a compromised extension account being used to call expensive international or premium-rate numbers; the bill may only be noticed at the end of the month. Use strong, unique passwords for extension accounts, do not expose the management interface directly to the internet, disable international calling where it is not needed and keep the PBX software up to date. If there are settings that alert you to unusual call volumes outside working hours, turn them on.
Whether your existing numbers can be moved to the new system, how emergency calls will work, and the conditions that apply to each line type can vary from operator to operator. Confirm these points with your operator before planning the migration.
Call recording
Recording calls has become easy, but recordings contain personal data. On which calls are recorded, how people are informed, how long recordings are kept and who can listen to them, Turkey's personal data protection legislation (KVKK) and the related guidance should be followed, and legal advice sought where necessary.
Planning the migration
Start by mapping the current situation: how many extensions there are, which are actually in use, how calls are routed and which numbers customers know. Don't forget devices connected to analogue lines, such as fax machines, alarm systems, lift phones or door entry systems; these may need an analogue adapter, or some may need to stay on a separate line.
Next, decide between an on-premises PBX and a cloud PBX. With an on-premises PBX, hardware, updates and backups are your responsibility; with a cloud PBX that burden moves to the service provider, but the monthly fee and dependence on the internet increase. Check whether your phones and network infrastructure, particularly PoE and QoS support, are ready for the switch.
If possible, migrate in stages. Trial the system with a small team first, monitor call quality and routing for a few days, then expand. Briefly show users how to do common tasks such as transfer, hold and conference calls on the new phone; a good share of complaints about a new system come down to different habits.
Checklist
- Have extensions, call routing and devices connected to analogue lines been listed?
- Has the difference in responsibility and cost between an on-premises and a cloud PBX been assessed?
- Do the network switches support PoE and voice priority (QoS), and is a separate voice VLAN planned?
- Has the internet line's upload capacity been assessed against the number of simultaneous calls?
- Are the PBX, switches and modem on a UPS, and where will calls go if the internet is down?
- Are extension passwords strong, international calls restricted and the management interface closed to the internet?
- Have number porting and emergency calls been confirmed with the operator?
- If calls will be recorded, have notification and retention rules been set?