Late in the career of 5XB, junctor group size and thus link efficiency of the largest offices was increased by the use of auxiliary line link (ALL) frames. The ALL is a bay with ten junctor switches, divided as usual into left and right halves. One half has on its levels the line links of an even numbered LLF, and on its verticals, the junctors of the neighboring odd numbered one; the other half is vice versa. By this means, each LLF can use the junctors of its mate, if the marker failed to find an idle path on the first try. Since they are odd and even, their junctors appear on opposite sides of the trunk junctor switches, thus giving access to the mate trunk links as well. Connections through the ALL were only used in heavy traffic periods.