Business VoIP PBX Systems

Karagiannis Security Systems® designs, installs, configures and supports VoIP PBX systems for businesses. The right solution does not start with choosing a box. It starts with understanding how calls actually need to move through the organisation: which numbers are in use, who should answer, what should happen when a line is busy, how working hours are handled, what remote users need and what should happen when a call is not answered.

Before proposing a system, we document the call flows and review the network that will support the VoIP service. The objective is for the PBX to fit the way the business operates, rather than forcing the business to adapt to a poorly planned telephone system.

What we can provide

Depending on the installation, our work can include:

• VoIP PBX installation and configuration,
• extensions and ring groups,
• IVR and recorded greeting flows,
• inbound and outbound call routing,
• call queues and distribution rules,
• working hours, public holidays and out-of-hours scenarios,
• voicemail and voicemail-to-email,
• SIP trunks and compatible IP lines,
• remote users and mobile applications,
• branch connectivity where the network architecture supports it,
• call history and reporting,
• call recording where required and used within the applicable legal framework,
• callback, blacklist, conference and other features supported by the selected platform,
• remote technical support where technically possible and on-site support by appointment.

We do not assume that every feature is useful for every organisation. The system is configured around the functions that are genuinely required and can be supported properly.

Call flow comes first

A PBX may offer many features, but its value is seen in what happens to a real incoming call.

A typical flow may include:

1. an introductory message,
2. an IVR choice or direct routing to a team,
3. ringing several extensions according to a defined rule,
4. placing the call in a queue when users are busy,
5. switching to a different scenario outside working hours,
6. sending the call to voicemail or another agreed destination if it remains unanswered.

These flows are designed before the final configuration so that each scenario is understood before the system goes live.

IVR, queues and ring groups

IVR is useful where calls genuinely need to be separated between departments or services. It is not something we add automatically. In a smaller organisation, routing a caller directly to the correct team may provide a better experience than adding unnecessary menu steps.

Queues and ring groups can improve the way calls are distributed when several people serve the same function. The configuration is based on the actual operating model rather than a single template applied to every business.

Remote users and branches

A modern VoIP PBX can support users who are not all in the same location. Depending on the platform and the network, an extension may be used from a compatible desk phone, computer application or mobile device while remaining part of the same company telephone system.

Separate sites or branches can also be included in a common design where the network connectivity and architecture allow it.

Cloud or on-premise PBX?

There is no single answer that suits every business.

For some installations, an on-premise PBX provides the right level of local control. In others, a cloud architecture may offer different advantages for management or remote users.

The choice depends on the lines, the network, the number and working pattern of users, the existing handsets and the level of control and support required.

The network directly affects VoIP

A telephone system does not operate independently of the network. Switches, VLANs, internet access, routing, PoE, cabling quality and configuration can all affect day-to-day VoIP operation.

Where required, we combine the PBX project with network and structured cabling services. Being able to assess both the PBX and the network layer is particularly useful when determining whether a problem is caused by the telephone system, the local network or the connection itself.

Migrating from an older telephone system

Replacing an older PBX requires planning. Existing lines, handsets, call flows and network infrastructure should be reviewed before the migration begins.

Where practical, the change is prepared in stages with testing before the final switchover. We do not promise that every migration can be completed with zero interruption. The objective is to reduce operational risk and make the planned changes clear before the new system enters production.

Equipment

Depending on the project, we work with Yeastar and Grandstream PBX platforms and compatible Grandstream, Yealink and Fanvil handsets. Brand is not the only selection criterion. The system must match the required functions, compatibility and long-term support needs of the installation.

You can also browse our related Telephony and PBX, PBX systems and telephone devices categories where available.

Support and maintenance

Support may include remote diagnostics where technically possible, on-site work by appointment, call-flow changes, user additions, SIP trunk checks and troubleshooting across the PBX or network layer.

For installations that require an organised support arrangement, maintenance services can be agreed according to the actual requirements.

Why Karagiannis Security Systems®

Karagiannis Security Systems® has been operating since 2006 and maintains direct technical responsibility for the projects it undertakes. Our work also covers networks, racks, switches, security systems and IP infrastructure, which is especially relevant in VoIP projects where the telephone system depends directly on the network.

The company holds a Private Security Services Company operating licence issued by the Hellenic Police, Protocol No. 3015/39/60/4343-e.

Frequently asked questions

How much does a VoIP PBX cost?

The cost depends on the number of users, lines, required functions, handsets, the existing network and whether the solution is cloud or on-premise. We therefore document the requirements before preparing a proposal.

How long does installation and migration take?

It depends on the complexity of the installation, the lines, the number of users, the required call flows and whether existing infrastructure is being retained. The migration is planned and tested before the final change.

Can I keep my existing telephone numbers?

In many cases yes, but the process depends on the provider, the type of line and the applicable portability or conversion procedure. This is checked before the final solution is confirmed.

Cloud PBX or a system on my premises?

Both can be appropriate. The decision depends on the working model, the network, the handsets, remote-user requirements and the level of management and control needed.

Do I need to replace my old PBX?

Not necessarily. We first assess whether the existing system can still be supported and whether it meets current requirements. Replacement becomes more relevant where a system is End of Life, parts are unavailable or new requirements would otherwise require repeated compromises.

Can my extension also ring on my mobile?

Compatible VoIP platforms can use a mobile application or another supported method so that a user remains part of the PBX when away from the office. The exact behaviour depends on the platform and configuration.

Design the call flow first, then choose the PBX

If you need a new telephone system, an upgrade to an existing PBX or an assessment of your current installation, contact Karagiannis Security Systems®. Call +30 210 7781577, Monday to Friday 09:00 to 16:00, or use our contact page to describe your requirements.