Since 7.2x firmware they all support all languages and got exactly same firmware, there are no more differences between german and international versions but additional plugs/adapters.
If you already have adapters you can reuse them, DSL-port pin layout is the same on all Fritz-modems (could only have additional POTS and ISDN input).
So you can even use cables from other vendors (RJ45 and RJ11 would fit too) as long as middle 2 pins are DSL-input, next 2 are POTS input on other models like 7590, 7530 does not support POTS only VoIP or NGV!
If you still got POTS you cant use 7530(ax) for telephony features like DECT, fax and answering machine.
I only found international version of 7530ax with part number 20002930, you have to ask your dealer for uk-adapters whether they are included in his package.
You only have to keep an eye not to bid on special vendor versions mostly cheaper on ebay and often have some limitations if you dont know they will match your line, they might be identified by different housing (colour and printing) and part number.
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