Sender ID:
Slovakia Tmobile (23102) does not support numeric Sender ID and all numeric senders will be overwritten with 'SMS' in order to ensure delivery.
Content:
There are no additional content restrictions beyond those in our Acceptable Use Policy
Other features/restrictions of note:
Delivery Receipts:
Handset delivery receipts are supported.
Links:
Global SMS Features Overview (Outbound only)
Global SMS Numbers Features Overview