NS&I (Ernie) have now introduced a new online sign-on validation system which involves them sending a one-time passcode via a call to your mobile - my call and the code never arrive despite repeated attempts.

This system works for my bank but not NS&I - I have called them to report the problem and am awaiting a solution - just wondered if anyone else has had the same issue and how it was fixed.

I log in easily it requires NSI number, surname and password. I think when the system first changed I required to get the code which I got by phone call. Now I just need details I've mentioned and after a short wait it authenticates me and I'm in. You mention numerous attempts? It only gives one three attempts if any errors and then locks you out totally. If you get locked out it is a very long process to get back in as they send the details by post . I know as happened to me and it was a long slow process to get back in.

Just a thought you haven't changed your phone number since registering your initial details with NS&I? To send your one time passcode they will only use the telephone number you have registered in your account details. It then comes to you as a phone call and they read out the passcode, you can get them to repeat it by pressing a key etc. If you have changed your number they will be ringing the old number.

Thanks but they have the correct mobile tele number - their call never comes through.

Prior to this yes I was entering NSI number, surname and password and everything was fine.

The two factor identification system seems to be working fine for me on the phone and on the PC. Bobd22 makes a good point about possible phone number errors. When (eventually) you work out where the codes are going, make sure you accept the option to "register this device" and that will stop the system asking for validation codes on many future logins.

Is your telephone number a standard mobile or landline? I use a UK mobile number as I have a dual SIM phone.

I found this on the NS&I authentication help page

Why am I not receiving an automated phone call?

Your phone network could be automatically blocking the call or sending it to a junk voicemail folder. To unblock the call, you may need to add the following numbers to your networks VIP list:

08085 007 007

I've just installed the NSI app on an ipad which has never been used with NSI and it installed and authenticated first time, so the system is working. The code came through in less than ten seconds

Are you using a pc or an app?

Spanish mobile but the NS&I helpline guy said this was acceptable this morning when I phoned them.

Yes thanks for that but I have added their number to my contacts.

Using a PC and I was signing it OK until they introduced the new system.

Suggestion, turn your phone off and reboot

The authentication codes are standard SMS messages, so maybe reconnecting to the messaging system may unblock it.

I used to get these codes sent to my Spanish SIM but it was only because I was using a different laptop. They seem to require you to use the same device when you log in. If you use a different one they start to get suspicious and send you codes.

I used to get these codes sent to my Spanish SIM but it was only because I was using a different laptop. They seem to require you to use the same device when you log in. If you use a different one they start to get suspicious and send you codes.
Anyway I am just going to try it as yesterday my son said his bank app show 3 × £100 NSI payments for the month if April which seems an usually high win for 1 month!!!

Once you have authenticated a device using the 2 factor code their system recognises that device and you log on with normal details. If you use a new device you need to authenticate using 2 factor to authorise that device. I have a phone tablet and Chromebook all authenticated and remembered by their system

If it's a non UK number the message comes as a phone call not SMS. They only SMS UK numbers I believe?

Couple of further observations, SMS message comes from NS&I but when I check the details of the message there is no sender number. Is it possible your phone is blocking unknown numbers or anonymous texts? It's always possible that you've "blocked" something previously and now the authentication messages are being caught in the same filter.