There's a lot of confusion about "e-call" systems. They are a legal requirement on new cars. It's part of a type approval process for all (volume) cars. I say that, because there are other, less onerous type approval and individual approval routes available for niche vehicles.
However, type approval regulations cease to apply at the point of first registration. Therefore, it's illegal for a car manufacturer to disable or delete the e-call system prior to registration, but once registered, there is no national legislation in place that obliges you to have it. Some manufacturers will, therefore disable it, but might make you sign a disclaimer saying that if you die a slow and agonising death in a ditch at the side of some remote road, undiscovered by any passers-by, it's on you. (...or words to that effect)...