A、Damage to the equipment. B、The man’s wrong operation. C、The line upgrading. D、It was unclear. C女士回答说：可能由于电信公司的电路升级而造成了一些用户的电话信

W: Good afternoon. This is Jane speaking. How can I help you?
M: Hi, I am calling in regards to a cell phone I bought from you a while back. I am afraid there is something wrong with the reception signal on my hand phone. I can’t seem to get incoming and outgoing calls and it always gives me a busy signal.
W: Could you tell me how long this has been happening? I ask that because it will likely tell me whether the problem is with your equipment or reception.
M: A couple of days ago. Initially I thought it could be the hand phone’s problem but then I realized it was probably the receiver signal.
W: Please give me your number and I will check whether there is any problem on the line.
M: 9988777.
W: Thank you. Please hold onto the line and I will get back to you in a minute.
M: Sure.
W: Sorry to keep you waiting, Sir. I have checked your number and everything is fine. It could be due to our line upgrading and sometimes it could affect certain mobile numbers. Our apologies for your inconvenience.
M: How long do I have to wait before the signal returns to normal?
W: Well, another couple more days. I will give this feedback to our technician and if the problem still exists after two days, please give us a call and we will help you to solve it.
M: Oh—but you bet I will phone if I don’t get this fixed soon. It’s not as if I can do without my cell phone for very long.
1 What is the problem with the man’s cell phone?
2 Why does the woman ask the man how long the problem exists?
3 According to the woman, what could have caused the problem?
4 What does the man imply at the end of the conversation?