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Vodafone Prepay Sim Cards


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We have had some problems with Vodafone PrePay SIM cards in New Zealand when used in GSM controllers and GSM Modems.


The new SIM card works fine, but when the SIM credit runs out, we have found that end users will often remove the SIM card from the equipment and load it into a phone, ring Vodafone and increase the credit on the card.

At that point, when the refit the card into the modem or controller, it will not work.


I have been advised that Vodafone do not change anything and it has been suggested that the problem is that the equipment is damaging the card.

The SIM card will still work on the phone in which it was updated and will work to varying degrees in other phones.


Having got hold of one of the "damaged" cards, I have done some analysis and am firmly of the belief that in the proces of updating the credit on the card, Vodafone New Zealand are dynamically altering the control settings on the card.

I found that the SIM card would recieve texts in Phone A but would not send them. It would send and recieve texts in phone B. An unaltered card would send and recieve in both phones.

To rejuvinate the SIM card, I fitted the card to a phone, (a Samsung GT I5510) and checked all the APN settings. - I did not alter anything, but after that I was able to send and recieve texts from this phone. Checking the APNs updated something on the SIM card.

I refitted the card into the modem, but it would still not send TXT messages. I discovered that the SMS service center number on the card was blank, so I used the AT+CSCA command to reset the service enter number back to +6421600600 and the modem burst into life.


Bottom line, either use an on account SIM card, or update your credit on line via the Vodafone web site.

GSM modems, MSM controllers and overseas phones do not have the APN data or the SMS service center data loaded into their firmware so are totally reliant on the data being correct on the SIM card. If the data is not on the SIM carrd, the modem, controller or overseas phone will not operate.

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