Problem using Cardplus credit card online abroad

[magalan]

I have a Cardplus credit card issued through Creditwest Bank. Recently, while on an extended stay in Thailand, I tried to purchase flight tickets online. When I was transferred to the payment page and entered the Cardplus card number, an identity verification panel opened informing me that a PIN would be sent from Cardplus to the Thai telephone number registered with Cardplus. I should then enter the PIN in the Verification panel and the sale would proceed. However, no PIN was received from Cardplus despite 2 further attempts. I have now been informed that

"It is a problem with the mobile phone providers.
Unfortunately as TRNC is not a recognised country, not all SMS messages are accepted by various mobile providers. They can be seen as ‘Spam’ so are blocked.
CardPlus are aware of this and have been trying for a period of time to resolve this issue.
The SMS messages will be received when sent to a local TRNC phone number, however for other countries ( not just Thailand) the problem is intermittent and ongoing and there currently is no solution"

The reason given above is directly contradicted by the fact that I have had absolutely no problem receiving and using a PIN when accessing Creditwest online banking anywhere in the world. I have spoken to my mobile supplier technical department in Thailand, and they categorically deny blocking SMS messages from TRNC, and also that no SMS messages had been received in connection with the purchase mentioned above.
This means that the Cardplus MasterCard is useless for online purchases around the world, unless you have means of accessing a TRNC phone while you are away.

Has anybody had a similar experience when attempting to use a Cardplus credit card abroad?

[Groucho]

The trouble with SMS is that it is not recommended for use in mission critical applications, mainly because messages are sent to a messaging centre for onward transmission i.e. they are not instant even though at times they may seem quick. The SMS system takes advantage of latency in the network thereby utilizing spare capacity, if there is none the messages wait before onwards transmission. They also work on an 'ack and nack' basis so the sending messaging centre will retry to send until it gets an acknowledgement (ack) from the home network to say that it has successfully reached the destination or it gets a negative acknowledgement (nack) and re-transmission occurs... this is time limited usually to 7 days after which time the message is aged out and dumped. Each message is given a unique identifier by the phone/system originating it so you don't get network charged for multiple sends of the same SMS.

[magalan]

Thanks for that Groucho. Using your explanation, given that my local (Thai) mobile supplier tell me that no SMS messages have been received from the TRNC at the time I was trying to buy flight tickets, there is no "ack" or "nack" being generated. I have been unable to obtain any sort of response from Cardplus other than the one in my first post. I have asked them to email or phone but the silence is deafening - it's almost as if they are not bothered by the problem.