Quick answer
"I need a second phone line" almost always means one of three different things, and they cost very different amounts. You might need more capacity (two calls at once), a second number (a separate sales or bookings line), or a direct number for one person (a DDI). Only the first of those is really a "line". On a modern phone service all three are software changes made in minutes, with no engineer and no copper - and the one thing you cannot do is order another analogue line, because those stopped being available in 2023.
The commercial point I would make first: the cheapest second line is usually the one you do not buy. Businesses routinely add capacity they never use because the old copper world trained them to think in physical lines. Work out which of the three you need, and the bill takes care of itself. If you would rather we looked at your current setup first, get a no-obligation quote.
Which of the three do you actually need?
| What you said | What you probably mean | What you need to buy |
|---|---|---|
| "The line is always engaged" | Two calls cannot happen at once | More capacity - a channel or a user |
| "I want a separate number for bookings" | One more published number | A second number on the same service |
| "Jane needs her own number" | A direct number for a person | A DDI |
| "I want work calls off my mobile" | A business identity, not a second line | A number that rings your existing phone |
| "We need a line for the card machine" | A device migration, not a phone line | Talk to your card provider first |
| "We are hiring three people" | More seats, and possibly more capacity | Users, then check concurrency |
The last two rows are where money gets wasted. A card terminal that used to dial out does not want a phone line at all any more, and hiring people does not automatically require more simultaneous calls - three new staff in a five-person office rarely change the peak. The terminology in that first column is unpacked properly in multi-line phone systems and channels.
The five ways to add a second line
| Approach | What it gives you | Best for | Cost shape (illustrative, August 2026) |
|---|---|---|---|
| Extra number on your existing service | A new published number routed wherever you like | Separate sales, bookings or accounts lines | Often included, otherwise a small monthly fee |
| Extra user or seat | Another person answering, with their own handset and number | Growing headcount | Per user, per month |
| Extra channel on a SIP service | One more simultaneous call into your existing phone system | Businesses with an on-site system | Per channel, per month |
| A second digital line | A genuinely separate line and number | A physically separate location or a completely separate function | Lowest standalone monthly cost |
| A business mobile with a divert | A number that follows a person | Field work, out-of-hours cover | Cost of a mobile plan |
The first row is the answer far more often than people expect, and it is the one providers volunteer least. Adding a number to a service you already pay for is a configuration change. Adding a second service is a second bill, a second contract and a second thing to cancel later.
Worked example: a shop that wants an orders line
An illustrative case we see constantly. A shop has one number. Customers ring it to ask if something is in stock, and trade customers ring the same number to place orders, and the two keep colliding.
The instinct is to buy a second line. The cheaper answer is usually:
- Add a second number to the existing service and publish it as the orders line.
- Route it to the same handset but with a distinctive ring or an announced label, so whoever picks up knows which hat to wear.
- Add one extra channel so the two numbers do not block each other at the busiest hour.
- Send the orders number to voicemail-to-email outside trade hours.
That is one small monthly increment rather than a duplicate of everything, and it can be undone next month if the split turns out to be unnecessary.
Worked example: keeping work off a personal mobile
The other common case is a sole trader or a small team handing out personal mobile numbers and regretting it.
Here the useful distinction is between the number and the device. You want a business number - ideally a geographic one that matches where you work - which rings the phone already in your pocket. In practice that means a number on a hosted service with an app, so outbound calls present the business number, inbound calls can be switched off at 6pm, and if the person leaves, the number stays with the business rather than walking out with them.
That last consideration is the one owners tend to notice too late. A customer relationship attached to a personal mobile number is not a business asset. For the mobile side of the same problem, see our guide to a second business phone number.
Why you cannot just order another line any more
It is worth being blunt about this, because businesses still ring up expecting to. New analogue lines have not been orderable since Openreach's stop-sell in September 2023, and the network itself closes on 31 January 2027. There is no route to a new copper line at any price.
That is not the obstacle it sounds like. What replaced it is faster and cheaper: a number or a channel added in software the same day, with no engineer appointment and no install charge. But it does mean the phrase "get another line put in" no longer describes anything real - see Openreach stop-sell explained for what is and is not still orderable.
Do not over-provision
Because capacity is now easy to add, it is also easy to add too much - and unlike the copper era, nobody will tell you that you are paying for idle channels. Two ways to avoid it:
Measure before you buy. Your provider can tell you how many calls you actually ran simultaneously at peak last month. That number is almost always lower than the guess, and it is the only figure worth sizing on.
Buy for the peak you have, not the peak you imagine. You can add a channel in minutes when Christmas arrives, and remove it in January. The old instinct to over-order because ordering took six weeks no longer applies.
The one genuine exception is a business where a blocked call is a lost sale. If callers get an engaged tone rather than a queue, a little headroom is cheap insurance.
Choosing the number itself
A second number is also a small branding decision, and the options say different things:
- Another number in your local range. Reads as the same business, same place. Usually the right default, and simplest to publish alongside your main number.
- An 03 number. National, not tied to a town, and charged to callers at standard geographic rates. Useful if you serve customers well beyond your area code.
- A memorable or vanity number. Occasionally worth it for a public-facing bookings line, rarely worth it otherwise.
- A mobile number. Signals a person rather than a premises - fine for field staff, weaker as a main published number.
Whatever you pick, add it to the same places as your main number - website, invoices, email signatures, your Google listing - or it will not get used.
The bottom line
Adding a second line is no longer a copper-and-engineer job, and in most cases it is not even a second line. Work out whether you need capacity, a number, or a direct number for someone; add the cheapest of those to the service you already have; measure your real peak before buying channels; and remember you can add more next week if you were wrong. The expensive mistake is buying a whole second service to solve what a second number would have fixed.
Tell us what is going wrong with your current setup - engaged callers, mixed-up enquiries, or a personal mobile you want back - and we will tell you the smallest thing that fixes it: get a no-obligation quote or call 0333 006 9399.
Getting unknown calls on a business line? Our free UK phone number checker shows which network or provider Ofcom allocated any number to, and whether the range is in service — no sign-up.
Frequently asked questions
How do I add a second phone line to my business?
On a modern digital or hosted service you add a number, a channel or a user in software, usually the same day and with no engineer visit. Which of those you need depends on whether the problem is calls colliding, wanting a separate published number, or giving one person a direct number.
Can I still order a second analogue phone line?
No. New analogue lines stopped being available at Openreach's stop-sell in September 2023, and the copper network closes on 31 January 2027. Extra capacity and extra numbers are now software changes on an internet-based service instead, which is faster and cheaper anyway.
Does a second line mean a second number?
Not necessarily, and the distinction matters commercially. A second line usually means capacity for another simultaneous call. A second number is a separate thing that often costs little or nothing on a service you already pay for. Many businesses need the number and not the capacity.
How much does a second business phone line cost?
Adding a number to an existing service is frequently included or a small monthly fee. An extra channel or user is a modest per-month cost. A wholly separate second service costs the most and is rarely necessary - so establish which of the three you actually need before comparing prices.
Can I have a business number that rings my mobile?
Yes, and it is usually the right answer for a sole trader. A geographic number on a hosted service rings an app on your existing handset, presents the business number on outbound calls, and can be switched off out of hours. Crucially the number stays with the business rather than the person.
How many phone lines does my small business need?
Size on how many calls happen at the same time during your busiest hour, not on headcount. Your provider can tell you your actual peak concurrency from last month's records. Most small offices need noticeably fewer channels than they have people.
Should my second number be local or an 03 number?
A second number in your local range reads as the same business in the same place and is the usual default. An 03 number is national, is charged to callers at standard geographic rates, and suits businesses serving customers well outside their area code. Both are equally easy to add.