VoIP intercom recommendations

Hello

I'm looking for recommendations from folks for a VoIP intercom. The intercom will be installed on an outdoors security gate, and as such must be tamper/dust/water proof. Ideally it will connect to a SIP phone or IP speaker in some nearby indoors office.

The following product looks ideal (basic, but would do the job just fine) but is presently out of stock:

https://www.pbtech.co.nz/product/IPHESC720879/Escene-IS710-P-Intercom-Security-IP-Phone

Any suggestions similar to this model or advice otherwise would be great.

Cheers,

Dave