Good morning.
As you can read at
Neuer Eigentümer bei United Mobile: Lage für Kunden weiter unklar - teltarif.de News (in German language) United-Mobile was sold to Cubic Telecom from Dublin, Ireland.
You know Cubic as the supplier of the Maxroam Roaming SIM card, based on a BASE-Belgium SIM. BASE Belgium belongs to the dutch KPN Group, which is also the Mother of the German E-Plus-Group. United-Mobile (Germany) has/had an IN-Roaming-Agreement for issuing germany-based Mobile-Numbers in the E-Plus-Numbers-Range. Now think about the possible products out from this deal
At the moment it's unclear when and how the issued UM-Liechtenstein oder UM-Jersey SIM-cards will come back.
Its not known at this moment, if the well known United-Mobile Brand will remain or if the Customers will be served under the Cubic / Maxroam Brand in the future..
At the moment the're negotiations between Cubic and Jersey Telecoms, Liechtenstein Mobilkom and some other mostly unknown in-between-suppliers. Nobody knows (or says) at this time, if and when their service will come back in detail.
UM-Outage is now for 2 months. Compared with Globalsim/Isle-of-Man, which needed round about 6 months for their comeback, they've still a little time, but most old loyal customers could be lost, then, I think.
My personal advice: If you're interested in your UM SIM-Cards and Numbers, keep them in a safe place, and register on the UM website.