The gatecrashing book will be useful for you to get your hands on if you play to feature Pandora gates heavily in your campaign. I've not entirely completed it myself, but it contains more speculation than hard details on the workings of the gate - a major factor you have to know about the Pandora gates is they are VERY poorly understood. They have libraries of known co-ordinates which can usually be read and used to dial co-ordinates but those have a nasty habit of, say, completely rewriting themselves without warning. It's really up to you. Maybe some gates do and some gates don't - or a gate will only give you an 'incoming number' signal from this address but not from that one. Or maybe some gates are able to hide their 'called ID' when they dial. Xenotechnology like the Pandora Gates tends to be where the game stops being hard sci-fi and starts being sci-fi horror. So in that regards, my advice from a narrative perspective would be 'no' - because then when the next attack might come, or in what form, or where from is completely unpredictable, rendering each gate opening that more tense and worrying.