Thank you for your asking. Please provide us more information so that we could better assist you.
1. What is your model name: ZA550KL, ZA551KL or else?
2. Please provide us your current firmware version. Have you updated to the latest? https://www.asus.com/Phone/ZenFone-Live-L1/HelpDesk_BIOS/
3. What kind of signal is low, during calling, using the internet or using wifi? Please provide us your question details.