Hello,
UM has some problems with the UM423 SIM-Cards:
On some networks you cannot set up outgoing phonecalls at this time, you will receice the response "Network busy", if you try it.
As you know, all outgoing calls from the +423 SIM are setup by a Text-Message (SMS). This text-system doesn't work at this time. UM told me, there is problem is with a 3rd party supplier.
Incoming text-messages (SMS) on +423 should work. DATA Services on the contracted networks should work, too.
Inoming calls should work, if the calling carrier connects to +423-663.
UM distributes new UM+ SIM-Cards to their customers free of charge
Therefore UM decided to move their customer base to the +44-7937 (UK-Jersey) System
At the moment UM is sending new UM+ (+44-79379...) SIM-Cards free of charge including 10 EUROs account, to all their customers, if they know their postal adresses. If they don't know your adress, you can ask the Customer Care to send a new SIM-Card.
UM offers to transfer your UM423-account to your new UM44 SIM-card, which can be administrated at
United Mobile - Low rates for calls and internet abroad after registration.
On the back side of the information-letter, where the UM CEO explains the situation, you'll find the latest UM+ rate plan. UM has increased the number of Roaming countries for the UM+ SIM card quite a lot.
For the UM+ SIM Card you should use a "simple" mobile phone. Some Serie 60 Nokias don't work properly with the SIM-Toolkit Application on the SIM-Card, which controls the Calling procedure.
Background:
+423-663 Range from Liechtenstein is not only used by United-Mobile, but also by "Premium"-Services "lonesome ladies", strange shopping-hotlines etc.
Some carriers do not connect +423-663 any more, other carriers mix the numbers and connect to other Premium Services, which you may don't want to call at all.
So United-Mobile decided to "switch" to the +44 UK-Jersey SIM. The 423-SIM-Cards will maintaind for DATA-Transfer for a while, but UM is negotiating very hard, to get attractive rates for the DATA usage with the UM+ SIM-card. Data Services with the UM+ SIM are planned for late 2009.