I think 18 yuan includes integral display and color ring back tones, because in Zhejiang, such packages basically include such fees. Take Hangzhou M-Zone as an example, 40 yuan raccoon Longquan package includes integral display, and general caller ID is included in the monthly fee.
If it is not included, CRBT can be cancelled with the same cost.
I suggest you check your own package online, which is basically introduced on Zhejiang Mobile website.