Execu/Tech Systems supports a 1 and 2 way PULL interface. An interface runs on the hotel's PMS server and at an interval, usually 2 - 10 minutes, reaches out to the CRS server via the internet and requests any reservation activity that's occurred since the last check. Any changes like a new reservation, modification or a cancellation are imported into the PMS. When using the 2 way interface rates and availability will be updated to the CRS as they change in the PMS every 2 minutes.

PULL interfaces do not require IIS to be installed because the interface application "pulls" the reservations from the CRS by requesting them via secure HTTPS.

Vertical Booking supports the 2 way PULL method.

The supported one way messages are found here: OTA / HTNG Limitations