You can open the door easily with http feature through the Line Key button on SP-R52 guard phones. You can open the door without answering the call thanks to the line key button. I added some images regarding this configuration underneath and I hope these images help you adjust the configuration.
1. Enable the open relay via http feature. Enable the switch part and write username and password according to the doorphone you already use to login the web gui of the doorphone.
2. Login the web gui of the guard phone. Click the Phone>Key/Display part. Pick the type as URL and write the value as http door open command.
Thanks.
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