Not to mention that the VS-VML comes configured for the ADIX-VS system, whereas any other voicemail system would have to be configured, in addition to configuring the VS. With the VS-VML, all you have to do is the company configuration: create mailboxes (with the new 128MB card .. the old cards were fixed at mailboxes 201-250), create menus (if needed/wanted) and configure the day/night time off-hook scheduling. With any other voicemail (a LINGO for instance) you would have to configure the voicemail to look for certain DTMF signals the VS would be sending to it, depending on the type of call that is going to the voicemail. There would be other config to do as well.

Stick with the VS-VML ... it'll be better in the long run, because, as was mentioned by JBean, if you decide in the future to upgrade to the full ADIX-APS system or the ADIX E-CS system, you can get an adaptor card which will allow you to bring your voicemail with you to the new system without losing any settings in it.