As far as I can find out it looks as if the following are all OEM versions of the same product:
Miocronet SP50xx
Immix Tel C3-FXS/FXO
Welltech 37xx
Euro Teletech VIP-400
Can anyone using these in the UK with either an FXO connected to a regular analogue line or an analogue port of an ISDN (BT Highway) line please post their phone and tone settings.