What different between "One Number users" and "OpenTouch Conversation"

[SonGiao]

Hi everyone!
I have a quotation of PABX and i not understand something. Pls help me.
"1 additional off-site any mobile phone user software license" what is it for? I saw that we have some specific licence for windows, android and Iphone, ("and 1 additional OpenTouch Conversation for iPhone user software license")
"and 1 additional OpenTouch Conversation for iPhone user software license"
What is different ?
what is it for? I saw that we have some specific licence for windows, android and Iphone, so, what is this license for?
Thank for your help.

[PlanoPCX]

'Off-site any number user' refers to the ability to have your extension divert (or dual ring) to an external number. A case for this may be to have your mobile phone ring in tandem to your desk phone.

the "OpenTouch Conversation for iPhone user software license" is the license to use the OTC Mobile application on iPhone. This app give you extra functionality such as directory look up, voice mail access and in-call features. There is a version for IOS, Android and Windows Mobile (in the case of OxO). An addition to OTC mobile (for IOS and Android) is the SIP companion, this allows VoIP calls from the mobile client to avoid voice minute charges.