in northern ireland, the situation was more complicated. while the primary reason for the changes was the lack of numbering capacity in belfast (01232), this was not the only reason. when std codes were introduced in the 1950s, northern ireland was allocated only 14 area codes for 34 charging groups. normal practice in great britain was to allocate one area code per charging group, but as calls to northern ireland were national rate from anywhere in gb, it was not seen to be necessary to differentiate between all of them. so, area codes covering multiple charge groups ("mixed" areas) were created; in practice this meant that some areas had longer area codes. for example, while enniskillen was allocated the area code 0365 (0ek5), kesh was allocated 03656 and lisnaskea 03657. as a result, numbers in enniskillen could not begin with 6 or 7, as this would conflict with those of kesh or lisnaskea.