eSIMratMSISDN (the phone number)
by RonyThe MSISDN (Mobile Station International Subscriber Directory Number) is the technical name of the mobile phone number: the one people dial to reach you, in international format. It is the public identifier of your line, assigned by the carrier, as opposed to the internal (IMSI) and hardware (ICCID) identifiers the public never handles.
Why it matters when travelling
Most travel eSIMs are data-only: they have no usable MSISDN. No number means no ordinary calls or texts on that line; that is why you keep your home line active alongside to stay reachable, and why WhatsApp keeps working (it is tied to your account, not to the active SIM).
Some eSIMs still show a “number” in the settings: it is often a technical identifier assigned by the network, unusable for receiving calls. Do not give it to anyone, it leads nowhere.
The misconception
“With no number on my eSIM, I will lose WhatsApp abroad.”
You will not: WhatsApp is attached to your account, verified once with your home number. It then works over any connection, data-only eSIM included. Your WhatsApp number stays the same, even if the home SIM is switched off during the trip.
What it changes when you compare
The MSISDN is a simple sorting criterion: do you need a local number (rare: phone bookings, local apps demanding a national number) or not? In 95% of cases the answer is no, and the cheaper data-only eSIMs are enough. The esimrat comparison flags offers with a number when they exist.
Compare eSIM plans by destination
The rat's tip: If a local step requires a national number (a delivery, a local taxi app), first check whether the app accepts your home number with its country code: it does far more often than people think, and it saves buying a number for nothing.
See also
Frequently asked questions
Why does my travel eSIM have no number?
Because a number is expensive to run (interconnection, regulation) and travel eSIMs target data. Dropping voice and texts allows far cheaper plans: your calls go through WhatsApp or FaceTime, your texts land on your usual line.
MSISDN, IMSI, ICCID: how do I keep them straight?
Three layers of the same line: the MSISDN is the public number (reachable), the IMSI is the internal network identity of the subscriber, the ICCID is the serial number of the medium (card or eSIM profile). You only ever give out the MSISDN; technical support asks for the ICCID.
Can I keep my number when moving to an eSIM?
Yes: converting your physical SIM into an eSIM at your carrier changes nothing about the number, it is the same line on a different medium. And while travelling, your line (and its number) coexists with the travel eSIM thanks to dual SIM.