I had a suspicion at first that this problem may be caused by congesture in network and assigning error MSRNs. Which might have meant a VLR prob.
However, since a landline number was calling me on my mobile where the person clearly said she wasn’t calling because not at home.. the MSRN point seemed wrong.
The only common factor I found here was that the mobile phones happened to be in or close to the locations where the erroneous CLIs were being generated.