Question 1

Hosted VoIP or an on-premises PBX: which one fits your business?

Accepted Answer

Hosted VoIP fits most small offices and any team with remote or home-based staff. An on-premises PBX fits larger sites with heavier call volume that want the equipment and its configuration under their own roof. With hosted VoIP, the phone system runs in the provider's data center. Your handsets reach it over the internet, you pay a monthly subscription, and the provider handles updates, security patches and capacity. Adding a user is a change in a web portal, not a hardware purchase. With an on-premises PBX, the call server sits in your building. You own it outright, calls between desks keep working when the internet drops, and it connects directly to paging, door intercoms and call-center features. The trade-off is that backups, updates and eventual replacement are your responsibility, and remote workers need a VPN or a properly configured edge device to reach it.

Question 2

What is SIP trunking?

Accepted Answer

SIP trunking replaces the traditional phone lines coming into your building with a voice connection delivered over your internet service. SIP stands for Session Initiation Protocol, the standard that sets up, manages and ends calls between IP phone systems. A SIP trunk is the virtual circuit between your PBX and a carrier that hands calls to and from the public telephone network. Instead of a fixed number of physical lines, a trunk carries as many simultaneous calls as you have channels, and channels can be added or removed as your call volume changes. SIP trunking applies mainly to on-premises PBX systems, since a hosted provider already includes the carrier connection in its service. Businesses move to SIP trunks when the carrier retires their copper lines or PRI circuit, when they want several locations on one account, or when they want to keep a PBX they already own and drop the analog lines behind it.

Question 3

Can you keep your existing phone numbers when you switch systems?

Accepted Answer

Yes. Your business numbers belong to you, not to your carrier, and the carrier you are leaving is required to release them to the one you are joining. The process is called porting. The new provider submits a port request using the details on your current bill: the account number, the billing name exactly as the carrier has it, the numbers to move, and often an account PIN or a copy of the latest invoice. Mismatches in those details are the most common reason a port is rejected, so pull an accurate copy of the bill before you begin. Keep the old service active until the port completes. Canceling early can send the numbers back into the carrier's pool, where they are hard to recover. Toll-free numbers, fax lines and numbers bundled with an internet package each follow their own steps, so flag them at the start so nothing is left behind on the old account.

Question 4

What happens to your phones when the internet goes down?

Accepted Answer

With hosted VoIP, your desk phones cannot place or take calls while the internet is down, but the phone system itself keeps running in the provider's data center. Callers still reach your auto-attendant and voicemail, and calls can be forwarded automatically to cell phones or another location, so an outage at your building does not have to be an outage for your customers. Most providers also offer a mobile app that works over cellular data. With an on-premises PBX, calls between desks keep working because they never leave the building; outside calls depend on how the PBX reaches the carrier, so a system on SIP trunks loses outside dialing until the connection returns. The mitigations are the same for either design: a second internet connection from a different carrier, a router that fails over between them on its own, a battery backup for the network closet, and forwarding rules set up in advance rather than during the outage.

Question 5

What does your network need to carry voice calls well?

Accepted Answer

Voice needs three things from your network: priority over other traffic, power at the desk, and cabling that tests clean. Quality of Service (QoS) is the setting on your switches and router that lets voice packets go ahead of file downloads and video streams. Without it, calls sound fine on a quiet network and break up the moment someone starts a large transfer. Power over Ethernet (PoE) lets the switch power each handset through the same cable that carries its data, so there is no power brick at every desk and the phones stay up on the closet's battery backup during a power blip. The cabling matters more than most people expect. A run that was punched down badly or stretched past its rated length will pass web traffic and still cause choppy audio, because a voice packet that arrives late is simply dropped. Category 6 or better structured cabling to every phone location, terminated properly and tested, is the foundation the rest of the system sits on.

Question 6

How much internet bandwidth does a phone system need?

Accepted Answer

Less than most people expect, and the figure that matters is concurrent calls rather than headcount. A single call on G.711, the codec most systems default to, works out at roughly 85 kbps in each direction once the IP, UDP, RTP and Ethernet overhead is counted on top of its 64 kbps of audio. Ten simultaneous calls is therefore under 1 Mbps each way. Even a busy office rarely has every handset in use at once, and a third to a half of the phones is a reasonable planning figure. Upload capacity is the half worth checking, because an asymmetric connection advertises a large download figure and a much smaller upload one, and a call needs both directions at once. Capacity is also not the whole story: voice packets leave every 20 milliseconds and are useless if they arrive too late to play, which is why a connection with bandwidth to spare can still carry a bad call.

	Hosted VoIP	On-premises PBX
Where the call server runs	Provider’s data center	Your building
Typical fit	1–10 users per site, remote staff	10 or more users per site, paging, call center
Cost shape	Low upfront, monthly per user	Hardware purchase, lower monthly
Updates and backups	Provider’s job	Yours, or under a support plan
Internet outage	Desk phones stop; the provider’s voicemail, auto-attendant and forwarding usually keep working	Desk-to-desk calls keep working; outside calls depend on the trunk
Outside lines	Included by the provider	SIP trunks, sized to call volume

Business phone systems and VoIP installed in Central Florida

On-premise PBX phone systems

Hosted cloud phone systems

SIP trunking, lines and handsets

The people who ran the cable answer the phone

Common questions about business phone systems