BCD decoding

Gurus, Would it be possible to BCD decode a VSA value coming from the NAS? I'm working in 3GPP environment. Some of my older GGSNs are sending the 3GPP-IMEISV as it will be delivered to them by the SGSN, which is BCD encoded. They just put the information into the 3GPP VSA. Times ago, it was not clearly defined by 3GPP, how the GGSN has to handle this attribute. Now it is defined, that it must be a string of 16 digits, which will be handled correctly by our new GGSNs. I can separate the different behaviors by the NAS IP, but will need the readable IMEI in the string format for later processing. How would I put such a decoding into a DEFAULT area, possibly in the hints file? Regards Stefan