Phone calls and SMS work fine (but I don't use them much), mobile data also (and I do use it a lot). Rarely, typically during the use of mobile data, the modem disappears. Reboot always helps. Telegram and Firefox are somewhat slow but generally work reliably. Even calls on Telegram work (with the sound coming from the speaker). Noscript helps a lot. Calendar is not very usable. Heavy usage with high brightness can drain full battery in a couple of hours, but suspend lasts more than 24 hours.