New +377 Mobiles: Is Your Site Ready?

From 1 October 2026, every new mobile line issued in Monaco will get a Monegasque number. According to the Princely Government, new numbers will use the +377 country code in an eight-digit format announced as +377 377 xx xxx. The change follows new agreements between the Government's Digital Platforms and Resources Department (DPRN) and Arcep, the French telecoms regulator.

Existing Monaco Telecom customers with numbers beginning 06 keep them unchanged, and they don't need to do anything. So nobody's current number breaks next week. What changes is that from October onwards, every new resident, new employee, new company phone and new client who signs up locally will have a number that many websites, booking tools and CRMs have rarely or never seen before.

That is the practical issue for Monaco businesses. If your phone field rejects a new +377 number, the customer doesn't blame the numbering plan. They blame you, and they often leave.

What is changing, and why

Monaco has had its own international code, +377, since 1996. Mobile service in the Principality started in 1993 on the French system, and for decades Monaco Telecom has issued both French-range 06 numbers and Monegasque numbers. From October, new mobile contracts, both personal and business, will only get +377 numbers.

The Government presents this as a step towards control over its own numbering and as a security measure. Numbers issued entirely within Monaco's own network should make calls easier to trace and make number spoofing and phone scams harder.

For businesses, the effect builds up slowly. On 1 October almost nothing looks different. Over the next year or two, a growing share of your local customers, staff and suppliers will have a number format your systems were never tested against.

Where a new +377 number can break your website

Most problems come from well-meant validation written years ago. Check these areas first:

• Contact, booking and quote forms. Many forms default to France (+33) or assume a nine-digit national number starting with 6 or 7. A number like 377 xx xxx can fail the length check or get reformatted into something that can't be dialled.
• Phone input widgets. Country-picker libraries validate numbers against numbering-plan metadata. That metadata has to be updated when a country opens a new range. If your site bundles an old version, new Monaco numbers may be marked "invalid" until you update it.
• Checkout and account creation. On an online store, a phone field that won't accept a valid number blocks a sale. Look at your abandoned checkouts and form-error logs in October and November.
• Regex written by hand. Custom patterns like "must start with 06" or "exactly 10 digits" are common in older WordPress and custom-built sites, and they are the most likely to fail.

This is a small fix if you catch it early. Our web development team usually checks phone validation as part of a wider form audit, because the same forms often have other problems too.

CRM, SMS and messaging: the quieter risks

The website is only where the number gets entered. It then moves through several other systems:

• CRM and customer records. Store numbers in full international E.164 format (+377…) rather than as locally typed strings. Otherwise duplicate detection, lookup by caller ID and merges become unreliable. The same person may also show up under an old 06 number and a new +377 number if they change plans.
• SMS login codes and notifications. If you send one-time codes, booking reminders or delivery alerts, confirm that your SMS provider routes to the new range and that your own code doesn't filter numbers by prefix. A failed one-time code means a customer who can't log in.
• WhatsApp Business and messaging tools. These identify contacts by international number. Make sure templates, click-to-chat links and imported contact lists use the full +377 format.
• Marketing consent records. If you collect phone numbers for SMS marketing, the consent should stay linked to the right person when their number changes. Under Law No. 1.565 on personal data protection, overseen by the APDP, you need to keep personal data accurate and be able to show where consent came from. How this applies to your case is a question for your legal adviser, but clean, well-formatted numbers make it much easier. Our email marketing and CRM work covers this kind of data hygiene.

Your own numbers: new lines, listings and click-to-call

The change also affects your outgoing contact details. If your business adds a new mobile line after 1 October (a new sales phone, a new hire, a WhatsApp line for concierge requests), that number will be +377. Before you publish it:

• Use clickable tel:+377… links in full international format, not local notation, so they work from French, Italian and international phones.
• Update your Google Business Profile, directory listings and any structured data on your site so the same number appears everywhere. Mismatched phone details across listings are a familiar local SEO problem, and our SEO agency team sees it regularly.
• Check call-tracking, ad call extensions and email signatures so an old and a new number aren't both in use.

A one-hour checklist for October

You don't need a project for this. You need someone to test it properly:

1. Submit every form on your site with a number in the announced +377 377 xx xxx format, once the first real numbers are live. Try desktop and mobile.
2. Check the version of any phone-input library and update it if it's old.
3. Search your codebase and form plugins for hard-coded rules such as "06", "+33" defaults or fixed lengths.
4. Confirm with your SMS or messaging provider that the new range is supported.
5. Make your CRM store numbers in E.164 format and fix existing records in bulk.
6. Watch form-error rates and checkout abandonment during October and November.

The numbering format above is as announced by the Government and reported in September 2026. Confirm the details with Monaco Telecom or the DPRN before hard-coding any new rule. The goal is to accept valid international numbers, not to replace one strict pattern with another.

If you'd like a second pair of eyes on your forms, checkout or CRM before customers with new +377 numbers start arriving, get in touch. It's a quick check that heads off a slow, invisible loss of enquiries.