Sena's "Sena Utility" is good, but it lacks the ability to backup/restore and to share.
With this app you can backup the pairing list and group intercom of your Sena 20S into a directory named "senabackup" in your user default directory (normally that is the sdcard).
This is particularly useful when updating the firmware, because Sena recommends a factory reset in the process, which leads to an empty pairing list.
And you can easily share a pairing list/group intercom with your biker friends, via email, SMS, etc. - whatever App supports sharing plain text. Your friends can save that pairing list/group intercom on their cells and restore them into their Senas (Be aware: This will overwrite their existing pairing list/active group intercom, maybe they should make a backup beforehand!) and are ready to go the moment they reach the meeting point and can save the greoup the time it cost them to pair.
For the advanced: It is easily possible to set/overwrite individual locations in a pairing list/group intercom without loosing the others; technically every line in the files in "senabackup" is interpreted as a separate command.
Example: Three additional bikers have announced their appearence to today's tour, but their headsets are not in your pairing list/group intercom yet, but in a friend's with a 20S, and you want to add them to your pairing list/group intercom without loosing time by having to pair at the meeting point.
Procedure: The friend exports his pairing list/group intercom and sends you the file (for example via email or messenger).
Now you have two options: Either you also export your list, then open both lists with a word processing program on your computer, combine both in the desired order (important is not the order in the file but the memory location number: That's the number between 1 and 9 right after the "PDL"/"PD". It determines where in the pairing list/group intercom the entry will appear. If multiple rows have the same number the later one overwrites the prior one).
Or you reduce your friend's file on your computer to just the interesting lines and modify the memory location number so that the entries appear at the desired location in your list.
Either way, you then need to move the file onto your phone (or tablet) and insert ("restore") the list to your 20S via the app.