Are these times call times ie times actually on calls? A mobile phone can still used even if a call isn't being made.
Does a mobile actually record when it is being operated but NOT necessarily when it's being used to make a call or sending a text to some one? She could have been merely sorting through her messages/texts, but not necessarily sending a text or chatting to any one thus it may not record this as no call was being made or text being sent

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If this is the case and she had made a call whilst driving then finished this but continued to use her phone sorting through her messages/address book then she may well have still been concentrating on it and not on the road ahead. There may have been a serious miscarriage of justice if this is the case and I believe a perverting of the cause of justice. She simply did not see the cyclists and the changing road layout and conditions ahead as she was looking and concentrating on her mobile, perhaps composing a text, which when she subsequently came to a halt and began to realise what she had done, she deleted. Would the phone necessarily record this latter type of usage? Could it be established whether the phone was on or not ie when you call a mobile phone that is off, you get a message saying the phone is off, leave a message or call later. Surely the phone network provider would confirm whether her phone was actually on or off, in addition to call times and frequencies, am I right?