I have been using call blocker software for a few years which uses the caller ID data from incoming calls. Yesterday it blocked a call from a near relative labelling it "Invalid number". I later found out that the caller had just had there landline handsets replaced by service provider to work with "wifi". I am guessing this is VOIP. Could the change have altered the format of the caller ID string. My log shows the number correctly as 11 characters.
Any help appreciated.

