it appears you are trying to perform an attended transfer and from your description, yes the ext 102 should automatically go on hold as demonstrated here:
Please make sure you are using the correct control elements, because from your description the actual transfer step is missing, hanging up will simply disconnect the active and held calls.
If you perform the attended transfer on the Snom, you will need to place the caller on hold, call ext 101, speak to them and then hang up.
If you continue to have audio issues in the client, please send me more information about the setup in terms of devices plus the debug information per PM, so we can take a look at it.