I have had a recurring problem with my Caller-ID. Every few months it displays an incorrect 'time of call'. I report it to Orcon and it is corrected within a few days. The time recorded is identical on both my phone and fax. The last time it happpened it wasn't fixed within 2 weeks and I reported it again. They came back to me and said their equipment tested Ok  so it must be my end and wanted to know the models of phone and fax. The next person I spoke to insisted I got another phone as a further check!
The next day a call from Orcon while I was out. It had the correct time and I thought 'they have fixed it". but the following day I had a call and they wanted me to 'change the time zone ' on the phone. Do any phones have a 'time zone' setting?

Please can you experts comment on my analysis. I have LLU (homeline and broadband). The time recorded by phone and fax was identical (and about 12 hours previous  [GMT ??]  ). The caller-ID message has a checksum so two devices are unlikely to be faulty and invent identical times. My wiring or the cable to the exchange is not likely to cause interference affecting only the time part of the message and getting a valid checksum for ALL calls. The cause must be elsewhere - what's left -  the exchange (or whatever) which sends the message!!  Is that all valid logic??