Hi. Sorry I don't know the answer to your bus-specific query, but it might be helpful if I mention that the train line connecting Gare de Calais-Ville and Gare de Boulogne-Tintelleries provides a much quicker service than any public bus option, and the fares are very reasonable (no more than €10 each way). The distance between the towns is over 20 miles and I am not sure if it is possible to take a single bus route the whole way.
The rail route is operated by the French regional service TER, and the trains run every 1-2 hours and the journey typically takes 30-35 mins. Here is a pdf of the relevant timetable applicable until 10th December 2011 http://telechargement.ter-sncf.com/Images/Nord_Pas_De_Calais/Tridion/CM_BCD_ete2011_5v_tcm-26-18260.pdf
Did you want to travel by bus specifically to see more of the countryside and villages/towns?
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