How to Upgrade to Cloud Telephony: A Step-by-Step Checklist

Phone numbers List every main, direct-dial, toll-free and fax number, and note which carrier owns each one and whose name the account is in. Include the numbers people forget, such as the line used by an alarm panel, a card terminal or a door intercom. Each of these will either move to the new provider or need a different plan, so it is far cheaper to find them now than to discover them when they stop working.

Users and devices For each person, record their extension, the device they use and whether they work from home or travel. This tells you who needs a desk phone, who is fine with a mobile or computer app, and who needs both. It also tells you how many licences you are buying, and which people share a line, such as a front desk or a warehouse phone.

Voicemail boxes List every personal and shared mailbox, who monitors it, how often it is cleared and which greetings are recorded. Pick out any saved messages that carry legal, financial or customer-service value, because these are the ones worth exporting later.

Call flows Write down how a call travels today: the greeting, the menu options, the ring groups, the after-hours rules and the fallback when nobody answers. Draw it as a simple flowchart if that helps. Most old systems have routes nobody uses any more, so mark each branch as keep, change or drop, and leave the dead ones behind rather than copying them into the new system.

Current contract Note the end date, the notice period and any early-termination fee for the existing carrier and the phone system. These dates set your timeline, because you will want the old service running in parallel until the new one is proven. If the contract runs for another year, a phased move that starts with new hires or one department may be cheaper than paying a penalty.

Bandwidth A single call uses roughly 100 kbps in each direction, so ten simultaneous calls need around 1 Mbps up and down before anything else on the network is counted. Add up the calls you expect at your busiest moment, then leave generous headroom for video meetings, cloud backups and software updates. The guide to how much bandwidth VoIP needs breaks the maths down by codec, but a good rule is to keep upload speed in particular well above your peak call load, because upload is usually the smaller number on business broadband.

Call quality Three measurements decide how a call sounds. Latency is the delay between speaking and being heard and should stay under about 150 ms one way, jitter is the variation in that delay and should stay under about 30 ms, and packet loss, the share of audio that never arrives, should stay under about 1%. You can test VoIP call quality with free browser tools, and Calilio offers its own VoIP test that reports these figures from your actual connection.

Wi-Fi and routers Most "bad VoIP" complaints are actually bad Wi-Fi. Walk the areas where people take calls and check signal strength, move desk phones and fixed workstations onto Ethernet where you can, and use a router that supports quality of service (QoS), which lets you tell the network to give voice traffic priority over downloads. Also check that the router's SIP ALG setting, a feature that rewrites call traffic and often breaks it, is turned off if your provider recommends so.

Backup connection Decide what happens when the internet goes down, because it eventually will. The cheapest fallback is automatic forwarding to mobile numbers; the next step up is using the provider's mobile app over cellular data, which works as long as there is a signal; and the strongest option is a second internet connection or a 4G/5G failover router. Write the choice down and test it in the pilot.

Remote workers Home networks are the variable you cannot control, so ask each remote person to run the same call-quality test from their desk and to make a few test calls to a colleague. A short list of tips, such as using a headset, wired Ethernet where possible and closing bandwidth-heavy apps during calls, solves most problems before they are reported.

Number porting support Your numbers are the most valuable thing you are moving, so check first that the provider can port them. Ask which countries and number types it supports, whether toll-free and vanity numbers are included, what documents it needs and how long it usually takes. Some providers charge per number to port, and some limit porting to higher plans, so get the answer in writing. Calilio, for example, lets you port your existing numbers on every plan and also gives you a free local number in the US, Canada or the UK, which is handy for testing before the real numbers arrive.

Voicemail features Voicemail is more than a greeting. Check how messages are delivered (in the app, by email or both), whether voicemails are transcribed into searchable text, how long they are stored and whether shared mailboxes are supported.

Call routing options This is where providers differ the most, so it deserves a proper look. Call routing decides who hears the phone ring, in what order and what happens when nobody answers. The main ingredients are:

Users and roles Add each person, assign their number or extension and decide who has admin rights. Keep admin access to a small group, since an admin can change routing for the whole company. Set up teams (for example sales, support and front desk) at this point, because you will point call flows at teams rather than individuals, and then a new hire or a departure never requires a routing change.

Devices Install the app on mobiles and computers, set up any IP desk phones and test headsets. Remote workers should confirm their setup from home before the cutover.

Call routing and business hours Recreate the greeting, menu and ring groups from your flowchart. Set business hours so calls go to people during the day and to a clear after-hours path at night, and add holiday exceptions in advance, because forgetting a public holiday is the most common reason callers reach the wrong greeting. Where the old system had confusing routes, simplify them: an IVR menu with three or four options usually works better than a long one inherited from the old system, since callers tend to hang up before they hear option seven.

Voicemail Record greetings for each number and for after-hours calls, decide who monitors shared mailboxes and switch on email delivery. A good business greeting names the company, says when you are open and tells the caller what to do next. Send a test message to confirm it arrives in the inbox rather than junk, and use strong passwords and multi-factor authentication on mailboxes that receive voicemails, since they often contain account details and payment information.

Integrations Connect the tools your team already uses so calls are logged where people work. When VoIP and CRM integration is set up properly, an incoming call can pop the customer's record on screen, and every call, note and outcome is saved automatically against the contact.

Security Cloud phones are on the internet, so basic hygiene matters. Ask the provider about its VoIP security and encryption controls, use unique passwords, turn on multi-factor authentication and limit international dialling to the countries you actually call, which prevents toll fraud if an account is ever compromised.

Contacts and speed dials Export your directory to a spreadsheet and import it into the new system. Take the opportunity to remove duplicates and old numbers before importing.

Saved voicemails Most old messages aren't worth keeping, and they usually can't be transferred between systems. Where the old system allows it, save the few that matter as audio files in a shared folder before the old service is switched off, and note the date and caller for each.

Call history and recordings If you keep call logs or recordings for compliance or training, export them before cancelling anything and confirm where the new provider stores future ones and for how long. Recording also brings legal duties: the rules about call recording consent differ between regions, and some require everyone on the call to agree, so set up your greeting announcement and recording policy before you switch recording on.

Documents and signage List every place your phone numbers and extensions appear, such as your website, Google Business Profile, email signatures, invoices, packaging and printed material. If any number is changing rather than porting, this list is your update plan, and it is worth setting call forwarding from the old number for a few months to catch stragglers.

Gather the account details You will typically need the account holder's name, the service address, the account number, any PIN and a recent bill. These must match the old carrier's records exactly, and mismatches, such as "Street" versus "St" or an old company name, are the most common cause of rejected requests. If you cannot find the account number, ask the old carrier for a "customer service record" (CSR) that lists everything on file.

Allow time In the US, FCC rules require simple ports to complete within one business day, but business lines with multiple numbers, toll-free numbers or complicated setups can take several days or weeks, so check how long number porting takes and start the request early. A port that is scheduled to finish on the day before a long weekend is a risk, so plan around public holidays.

Keep the old service active Don't cancel the existing line before the port has completed. Cancelling early can release the number, and you may not be able to get it back. This is the most expensive migration mistake.

Agree a date and a contact Choose a port date and name one person who can answer questions from either carrier. For busy lines, consider porting in stages, starting with the less critical numbers, so you can confirm the process works before moving your main line.

Use temporary forwarding Until the port completes, you can forward calls from the old number to a temporary number on the new system, so the new setup can be tested with real callers. Carriers differ in what they ask for, so check the PIN and account details needed when porting a number from Verizon or from AT&T. In the UK, the planned PSTN switch-off makes this migration a deadline rather than an option, because lines that stay on the old copper network will stop working.

Register addresses Set a correct physical address for each office and for each user or device that could dial an emergency number, including suite or floor where it applies. Update the address whenever someone moves, and make this part of your onboarding and offboarding checklist.

Check the local rules In the US, Kari's Law requires multi-line phone systems to let people dial 911 directly, without a prefix like 9, and to notify someone on site when a call is made. The RAY BAUM'S Act requires systems to send a dispatchable location, such as a building and floor, with a call. Other countries have their own rules, and some providers do not support emergency calling on certain numbers, so confirm in writing how your provider handles it.

Tell staff Remote workers should know that the address on file is where responders will be sent, even if they are in a different place that day, and how to update it. A short reminder in your cutover announcement is enough.

Test it Don't place live test calls to emergency services unless your provider tells you how to do it safely. Ask whether it offers a test line or an approved procedure.

Test the basics Make inbound and outbound calls from every device type, try call transfers and hold, check caller ID and listen to the greetings from an outside phone.

Test voicemail Leave a message after hours and confirm that it is delivered by email, shows in the app and sounds clear. If transcription is included, check how accurate it is with real names and numbers.

Test call flows Walk through each menu option and each ring group, including the after-hours path, the holiday path and what happens when nobody picks up. Ask a colleague who has not seen the setup to call in and describe what they hear; they will notice confusing wording faster than the person who built the menu.

Test the fallback Switch off the pilot group's internet, or disable the primary office line, and confirm calls reach the mobile fallback. A plan nobody has tested is just a hope.

Collect feedback Ask pilot users what confused them, which settings they wanted to change and what they missed from the old system. Fix what you can, then write a one-page guide for the rest of the team.

Choose a quiet window Avoid month-end, a major campaign, a public holiday or a Monday morning. A mid-week morning, with the team in and the provider's support open, tends to work well, because you have the rest of the day to fix problems.

Brief the team Send a short note beforehand with what is changing, how to log in, what the new voicemail looks like and who to contact for help. Include a screenshot of the app, since most questions are about where to click.

Switch and test Once numbers have ported, call each main number from outside, listen to the menu, leave a voicemail and confirm it arrives. Test an outbound call from several devices, and check that the caller ID shows the correct number. If you use features like business hours, check that the right schedule is active.

Keep a fallback Know how to forward calls to mobile phones if something fails, and keep the old system's login and carrier details until you are confident. If the port was staged, you can pause the next stage.

Watch closely at first Check the call log and voicemail inboxes often during the first day, then daily for the first week.

Check the numbers Compare missed calls, voicemail volume and call distribution before and after. A sudden spike in missed calls often means a routing rule or business-hours setting was missed. If you can, listen to a handful of calls to hear what the caller experienced.

Review follow-up habits Are voicemails and missed calls being returned? Assign an owner for each shared number if responses are slow. For calls that arrive out of hours, an AI receptionist that answers, takes details and routes urgent matters can cover the gap.

Cancel the old service Once all numbers have ported and everything works, cancel the old lines and equipment within the contract terms, and recycle or return hardware. Ask for written confirmation that the cancellation does not affect any ported numbers.

Update documents Update your website, email signatures and any printed material that shows phone numbers or extension lists.

Train new staff Add the phone system to your onboarding checklist so new hires learn it from day one, and keep the one-page guide from the pilot up to date.

Cancelling the old line too early This is the single most expensive mistake, because the number can be lost. Wait for written confirmation that the port is complete.

Forgetting non-voice lines Alarm panels, fax machines and card terminals often use analogue lines that behave differently on VoIP. Test them with an adapter or keep a separate line for them.

Skipping the network test Poor Wi-Fi, an overloaded router or a weak upload speed will make any provider sound bad, and the provider usually gets the blame.

Leaving configuration to the last day Greetings, call flows and integrations take longer to set up than they seem, so finish them before the pilot.

Switching everyone at once A phased rollout limits the damage if something is wrong and gives you a real fallback.

Copying the old setup exactly A migration is the best chance you will get to remove dead extensions, shorten the menu and clean up greetings. Moving every old quirk across just moves the clutter.