An RTP stream starting is not a guarantee. There are situations where it will not start due to various conditions.
It seems you are really asking what types of stations can I use multiple registrations per device form of call recording with. The answer to that is SIP and H.323 only.
Analog phones do work with SSC and SO recording, but not multiple registrations (MR) per device - The MR mechanism only works with SIP and H.323 devices. There are other station types that MR does not work with (MET, MFAT, and some others most are pretty old at this point in time).
I suggest working with this ebook, even though there is missing information in it related to SIP endpoints (you have the FAQ that fills in those details) and split stream recording; overall it is a better starting point.
Depending on how things are configured the application is either starting a RTP stream between CM and your application or between the far end device and your application. If you are just getting started building your application, or testing with the DMCC Dashboard, I suggest disabling point to point media (direct media) in the network region that you are using for the DMCC side IP endpoints. This is a simpler starting point than trying to handle direct media on a point to point call. Once a call becomes a 3 party call (either through SO or SSC) or via multiple registrations it will be anchored on CM and the RTP paths pretty stable.