Many offices still run a traditional phone exchange installed years ago, with lines that cost money every month and a system that only one person knows how to change. VoIP (voice over IP) moves calls onto your data network and the internet. When it is planned well, it reduces costs, adds features and makes it easy to work from anywhere. When it is planned badly, it brings choppy audio and angry callers.
This guide explains the options, what call quality really depends on and how to migrate without losing a single call.
What changes with VoIP
- Calls travel as data over your network, instead of over dedicated telephone lines.
- Numbers are portable. In many cases you can keep your existing numbers when you switch.
- Extensions follow people. A softphone on a laptop or mobile app means the office number works from home or on the road.
- Features become standard: call queues, voicemail to email, call recording, auto attendant (IVR), reporting, integration with CRM and helpdesk.
Cloud PBX or on-premises PBX?
| Cloud PBX | On-premises PBX | |
|---|---|---|
| Setup | Fast, little hardware | Server or appliance in your office or data center |
| Costs | Monthly per user, low upfront | Higher upfront, lower per-user running cost |
| Control | Provider manages the platform | Full control over configuration and data |
| Scaling | Add or remove users easily | Depends on hardware and licenses |
| Best for | Growing, distributed or small teams | Larger sites, special integrations, strict data rules |
A hybrid design is also possible: a local system with SIP trunks and cloud features where they make sense.
SIP trunking in plain words
A SIP trunk is the virtual connection that carries your calls between your phone system and the public telephone network. It replaces physical lines. The quality and price of the trunk, and how well it is configured, strongly affect how your calls sound and how reliable they are.
What call quality depends on
- Bandwidth: a single call with a common codec takes roughly 80–100 kbit/s including overhead in each direction. Multiply by the number of simultaneous calls and leave headroom.
- Latency, jitter and packet loss: as a general guideline, one-way delay under about 150 ms, jitter under about 30 ms and loss under 1% keep calls sounding natural.
- QoS (Quality of Service): rules that give voice traffic priority over downloads and video so that calls stay clear when the network is busy.
- Network design: a separate voice VLAN, good switches and reliable Wi-Fi coverage if you use wireless phones.
- Internet connection: stable and symmetrical upload and download. A backup connection is worth it for businesses that depend on phones.
Most VoIP complaints are network complaints. If calls sound bad, the cause is almost always bandwidth, QoS or Wi-Fi, not the phone system itself.
Costs to consider
- Phone system licenses or per-user monthly fees.
- SIP trunk or call minutes.
- Desk phones, headsets or softphone licenses.
- Network upgrades, such as switches with PoE and QoS support.
- Setup, number porting and training.
- Savings from cancelled lines, cheaper calls and removed maintenance of the old exchange.
Migration step by step
- Review current use: number of lines, simultaneous calls, special functions such as fax, alarms and lifts.
- Check the network: measure bandwidth, latency and loss, and plan QoS and voice VLAN.
- Choose the platform (cloud, on-premises or hybrid) and the SIP provider.
- Design the call flows: reception, queues, departments, voicemail, working hours.
- Pilot with a small group before switching everyone.
- Port numbers and cut over outside busy hours, keeping the old lines active until all is verified.
- Train users and monitor call quality in the first weeks.
How we can help
Alficom delivers unified communications and VoIP systems, from cloud and on-premises PBX to SIP trunking, QoS, IVR, CRM integration and encrypted voice. We start by measuring your network, so the migration is based on facts and calls sound right from the first day.
