Many thanks for clearing it up! Really appreciate
Yesterday, I talked to a Service Center guy of Reliance Netconnect over the phone, and he also said modems are never infected by viruses - though he seemed too young and not 100% knowledgeable, and talking purely out of experience. Anyhow, the CDROM cannot be written locally, that's for sure. It certainly needs 'special tools' for that, and it seems writing into the memory chip also calls for 'user-acceptance', locally. So I suppose my modem is safe for use!
Many thanks once again!