Nil,
I’m looking at it from a GSM traffic point of view.The Qos or Gos (Grade of service) will ensure that if I have peaks in traffic there will be sufficient capacity available.Most suppliers recommend that you don’t dimension above 80% of the total capacity. In reality, if you have two signalling links you might might to consider redundancy, in that you dimension them upto 40% of their capacity.
So if one fails the other can handle the full load.
Hope this answers your question!