Answer to: Where do you get one?http://www.ebay.com/sch/i.html?_odkw=son... or https://www.amazon.com/s/ref=nb_sb_noss_...-alias%3Daps&field-keywords=sony+radio+antenna
Answer to: phone can't make call or smsIs your SIM card inside? Is your SIM service activated? Do you have balance remaining? Is airplane mode off? Check these before anything else.
Answer to: Differences between the 2 types of RAM.The RAM in Step 17 is the RAM for the actual system, while the RAM in Step 16 is for the SSD, which (correct me if I'm wrong) is used as a cache to make reads and writes faster by copying data to there first and then dumping it into the SSD itself.