Accountants: Protect Your Phone Line Before Your Busiest Season

The PSTN switch-off lands in the middle of tax season

January is the busiest period of the year for accountants and bookkeepers. Self-assessment deadlines, year-end queries and client calls about missing information all land at once, and most of that contact runs through a single phone line.

The UK’s old phone network, the PSTN, is being switched off completely on 31 January 2027, in the middle of the busiest stretch of the tax year for most practices. The date wasn’t set with accountants in mind, but it falls at the same time regardless.

Anyone that hasn’t moved to a digital line before this date faces more than a routine admin task in February. The phone system could stop working during the exact week clients, and HMRC, most need to reach it.

Why the timing matters for accountants specifically

Every business depends on its phone line. For accountants and bookkeepers, January raises the stakes in a few specific ways:

•             A missed call rarely stays a missed call. It can mean a missed client query days before a filing deadline, a missed new instruction, or a missed callback from HMRC, at the point in the year those matter most.

•             Clients hand over sensitive financial information and expect to reach the practice when it matters. A poorly managed switch risks more than downtime. It risks the trust built up over years of getting the basics right.

•             HMRC doesn’t move its deadline for infrastructure problems. Whatever happens to the phone line, 31 January stays fixed for client returns too.

Many practices also run multiple extensions, a shared reception line, or numbers tied to individual partners. Each of these depends on the same underlying network, so a switch-off that isn’t planned properly can affect more than one point of contact at once.

What happens when the network switches off

From 31 January 2027, the old copper PSTN and ISDN network stops carrying calls entirely. Openreach stopped selling new copper lines in September 2023, and providers across the UK, including TTNC, have been migrating customers ever since.

Some services move across automatically. Many don’t. Whether a practice’s main line, extensions, or anything else routed through it carries over cleanly depends entirely on whether a proper migration has taken place before the deadline, not after it.

What a well-managed migration looks like

Moving away from PSTN doesn’t have to be disruptive, and it doesn’t need to happen at the last minute. Done properly, a migration looks like this:

•             Every number the practice currently uses is kept and carried across, with no gap in service, so the practice keeps its business number through 2027 and beyond, and clients and HMRC never reach a dead line.

•             Calls follow the team rather than a single front-desk line, whether someone is in the office, working from home during peak season, or out at a client meeting.

•             The move happens on a day and time chosen by the practice, worked around its calendar and away from any filing-deadline period.

•             A clear timeline is set out before work begins, so the practice can plan around its busiest periods rather than the provider’s.

The cost of leaving it late

Early movers migrate on their own schedule, with full choice of provider and support availability. Businesses that wait until the final months compete for installation slots with everyone else who has also left it late, often when prices and availability are under more pressure.

Completing the move well ahead of autumn means one less thing competing for attention when self-assessment season begins.

For practices with several extensions or partner-specific lines, migrating each in turn takes longer than a single-line move, which makes early planning more valuable, not less.

How TTNC helps accountants get this right

TTNC manages this kind of migration end to end, with a UK-based support team and a named contact for each practice throughout.

This applies equally to sole practitioners with a single number and larger practices managing several partners and support staff. Each is migrated under the same process, with every current number retained.

TTNC handles:

• Every number currently in use, ported across with no gaps in service.

• A migration date built around the practice’s calendar.

• One point of contact throughout, removing the need to queue with a call centre during tax season.

• Clear, upfront terms with nothing added later.

The 2027 deadline is fixed. Early movers avoid the rush and secure current offer terms.