I would like to replace this with a smart handset that would dial an external number and allow me to open the door remotely. Is something like this possible?
If you want something really flexible and cloud-free, you may want to have a look at the doorpi project. Please note that doorpi requires a SIP server in your local network, e.g. a Fritz!Box router.
I am waiting for my Dahua VT2000A + VTH1510 to ship + POE switch
Video intercom with SIP integration
Requires some work but doeas all you said (plus much more if in the backend there is an asterisk pbx)
Unfortunately I wasn’t able to get a solution setup. My intercom is digital and nello doesn’t support it. I just checked your intercom on the nello site and it also doesn’t seem to be supported. Nello has recently ceased operation so it doesn’t look like there’ll be any further updates.
Nuki have released a similar product but again it doesn’t work with my intercom or yours. They are obviously still operational which means something could become available at a later date
I’m not sure if doorpi is an option for me with my intercom being digital.