Hi Manuel,
you will need a "Cisco Services for IPS" contract which is basically a variant of smarnet that also includes a license which is required to get signature updates.
You can use this tool to find what contracts are available and what each one offers:
http://www.cisco-servicefinder.com/
Disclaimer: I'm not in sales so you may want to double check with your CAM (I believe for partners there may be alternative options to distribute signatures to your customers).
hth
Herbert