I am not sure how it works in the Siemens Switch but as a generic rule in call routing all calls must be going thru some pre-analysis where dialled digits can be analysed and if reqd. extra digits are cut before calls go thru the routing analysis. In the preanalysis u shud be able to cut the nos. after 1414 if the subs. is dialing more than these 4 digits. As an example, in the preanalysis u wud have an entry for Mobile Originated Calls with type of number SUB (or whatever is the options available in Siemens other NAT and INT) and the digits to be analysed wud be 1414xxxx. You can then specify to cut digits xxxx by specifying the start point of cut digits=5
Alternatively, u need not cut the digits in preanalyse and in your originating call Tree u analyse the number 1414xxx and route it to a special route where u can then cut the dgits and then route it back to originating call tree. So in your originating tree u wud have two entries one for subs. dialing correctly 1414 and the the other 1414xxxx. In preanalysis also u wud have the two entries but no need to specify any digits to be removed in preanalysis.
hope this works and helps