So, I need to figure out if there is an intercom system (either landline style (Viking, etc., Wi-Fi (Ring.Com, Doorbird, etc.) OR other. The key is that the client wants to unlock the front door "Smartlock" of some sort, I don't want to install a old school electric strike.
Honestly, I'd really like to use something hardwired for the "phone" intercom and somehow open the front door. I haven't had good luck with Ring.Com style intercoms being great but very open to other suggestions, etc.

Do you have control system / automation platform or is this a standalone thing (intercom and door lock)?

At this point I'm just getting a bid together, so far a control system isn't really necessary (only 3 Sonos Playbars, a few Connect:Amps) BUT that doesn't mean I won't recommend one if it'll help with the intercom/ door "release" situation.

Doorbird does have on-board relays for door strikes/locks, as well as output to trigger standard doorbell chimes.

Using the DB app and C4 system, I have the key button on the app unlock my Kwikset deadbolt. Pretty sure you will need some control system to accomplish this kind of integration.

With pretty much any door intercom system, there is a gate/door trigger.
You can use that to trigger door lock.
Question is what type of door lock you have and what integration it offers.

On a basic side, look into IFTTT.

If control system is an option, Control4 can do this with any of their door lock modules without breaking a sweat.

Mobotix might work. They just introduced their MXDisplay+ Outdoor model which has Bluetooth support. The MXDisplay is a small touchscreen that mounts inside the house (but is weatherproof, hence the name), with a T25 camera station that would be at the doorbell location.

So, a visitor rings the doorbell (T25 button), and you receive a notification at the Display inside, or at your phone/ipad with the app. You can see and speak to the visitor, and open the gate/door.

It works as a standalone setup or can be integrated. Not the cheapest solution, but it's also got a million other feature which you may not actually want (RFID cards, message recording capabilities, etc...) The camera is a 180* recording camera that can save to an on-board SD card. All the devices are PoE powered as well, so the wiring is straight-forward.

I have an installation that went quite well, and has been reliable although I have NOT used any of the Bluetooth features. My only hiccup was a camera that acted funky right out of the box that I'm trying to return, and they're being reluctant with the RMA. Other than that, the support has been great.

EDIT: One more thing - I used the Mobotix because the homeowner required that there be a numeric keypad outside for visitors to key in a code to open the gate. That was something I couldn't get elsewhere (at the time).

Doorbird works with a couple of locks directly. Kevo, August, Lockstate.

The Doorbird can do this. I'd recommend using a pair of dry contacts inside the doorbird to ring a regular doorbell; then you'd use a dedicated iPad to answer the person at the gate and open the door.

This has the added advantage that someone not on site could answer the Doorbird on their phone and open the door... call it a gate in this case, for instance so a package could be left somewhere inside the gate. The Doorbird lets you look live, so you can tell when the person leaves the site, too.

Thanks for all the input!! It looks like the Doorbird can do what I need. I've put in a few August locks and though they're large inside they allow the outside to stay original.
Have any of you had direct experience with installing the Doorbird (with or without a "smartlock"). If so, can you give me some feedback?? I've been playing with a Skybell (Alarm.Com version) with not so impressive results. It uses the Alarm.Com app be it's very glitchy.

Siedle http://www.siedleusa.com/ does a great job with this. You can open your door at home or on the road through your phone.