Integrating your Sympl account with Flipkey or TripAdvisor (shared platforms) requires that you set up an iCal connection. This is a quick procedure, and when done with the method outlined below, you will have two-way synchronization. This will eliminate any potential double bookings by continuously exporting your Sympl calendar to FlipKey/TripAdvisor while importing theirs.
There are two parts to this process:
Calendar Exporting
Navigate to the Channels module from the top menu bar.

In the Channels List view, click the + Add Channel button.

In the Channels Overlay, select the iCal tab and locate the FlipKey/TripAdvisor option. Click Connect or on the + icon if there are existing connections.

In the Exported Calendars section, click the Add icon.

Select the rental from the dropdown list and click Export.

In the popup, copy your Sympl iCal URL.

In FlipKey/TripAdvisor: Locate and click the "Calendar" button at the top of your screen in the main menu bar.

On the next page, click the "Import" button on the right side of the screen (under "Sync more calendars").

When the "Choose Calendar to Import" page loads, you will select "Other". On the subsequent page, you will be able to paste your exported calendar URL into the URL field and give your calendar import a name.

Once complete, your FlipKey/TripAdvisor calendar will have synchronized updates from your Sympl account! Now you just have to do the reverse..
Calendar Importing
In FlipKey/TripAdvisor: On the "Calendars" page, you can locate and click the "Export" button (under the "Sync more calendars" heading).

The subsequent page will provide you with a calendar URL - copy this to your clipboard and return to your Sympl dashboard.

In Sympl: Navigate to the Channels module from the top menu bar.

Click the + Add Channel button.

In the Channels Overlay, select the iCal tab and locate the FlipKey/TripAdvisor option. Click Connect or on the + icon if there are existing connections.

Scroll down to the Imported Calendars section and click the Add icon.

Complete the required information:

What Happens Next?
Sympl will import all of your FlipKey/TripAdvisor bookings and blocked dates.
All imported Flipkey/Tripadvisor events become Hold Events in Sympl
iCal is a calendar link only. You will want to continue managing rates in Flipkey/Tripadvisor
You can convert Hold Events to Bookings in Sympl and enter additional info, by clicking on the Hold Event in your Sympl calendar and pressing "Edit", then "Convert".