Having been a client of this company between 2008 and 2020 If I’m honest I always felt like I was treated like nothing more than a number on a spreadsheet. The service and rates were fine but it was clear that you were an instrument of profit and nothing more. Furthermore some mobile networks do not connect to all of their number ranges and so if you have an 08x or 09x number from them then you might find that up to 20% of your customers calling from a mobile phone could not get through as some may hear a “this number is not recognised / this call cannot be connected” message although it depends on the number range/prefix you have. Therefore unless you can live with what could be up to a 10-20% decrease in call volumes from your advertising campaigns then in my opinion I’d say you should consider using a large network like BT to get your numbers from instead.