SMS gateway for Dynamics 365 - sms-gateway

Question

First of all, I have to say that I am NET developer (C#) and my knowledge on Dynamics 365 is pretty limited. Nevertheless my employer thought that I am good enough to make that thingy from post title :)
After couple of hours researching and reading, I found this video https://www.youtube.com/watch?v=6LwZLoXS6jo which address on how to create and send SMS from Dynamics. I am aware that this require me to create new Dynamics entities, at least SMSMessage and SMSMessageTemplate, but at least I found out how to do this :)
I understood everything stated there, but as i already said, due to my lack of knowledge on Dynamics 365, I got problems with (probably) basic things regarding Dynamics.
Here are those problems:
1. As far as I can tell, in order to build SMS gateway, first thing I need to do is to add new menu item inside Dynamics 365. I presume that this new menu item should reside inside 'Contacts' menu (contacts.jpg, marked with red box) but I am not sure on how to achieve this. Please note, I do not want someone to provide me with some magic solution, I just need someone to provide me with valid links that I can use to learn about this and solve my own problem :)
2. When new menu item is in place, and user click on it, I would like to open up a form for user to select SMS template that will be used and maybe setup some other values. Same again, U do not need to help me with exact code, just with some usable links :)
3. Inside that form that user will open on menu click, I would like to know how to get list of selected contacts (from grid at contact.jpg)
When I (finally) have that list of contacts, I will create SMS entities mentioned above (video link) and everything will fall in place and (hopefully) work.
I am aware that this is probably too much to ask, cause Dynamics 365 is rather complex, and people are spending great amounts of money and their time learning to became Dynamics developers, but without help, Dynamics is making me running in circles chasing my own tail :) and getting nowhere.
Also, I will be using online Dynamics 365 so bare in mind that any solution should work with it.
if any of U think that I missed or got something wrong, please let me know.enter image description here

Answer 1

So basically to get you started, you should:
1) Create a solution in Settings => Customizations => Solutions
2) Add contact entity to that solution (by choosing "Add existing" under Entities pane). Don't click "Add all assets" you will need only contact metadata to get going
3) Create jScript file and add a web resource to CRM (nothing really complicated, just go to web resources in you solution and click "Add new" and specify type of your web resource as jScript and target your file).
4) Now download http://www.xrmtoolbox.com
5) For now you are interested only in plugin "Ribbon Workbench"
6) Now simply choose your solution and contact - you will see command bars for contact homepage, list and form. This is pretty strainghtforward - simply drag and drop a button wherever you like, create a command using workbench and bind the button with the command (simply choose it from a drop-down). The command you are interested in is Custom Javacript. Here you specify your web resource and name of the function that you want to call. You can also specify parameters that should be passed inside your function for example ids of selected items (if you are on the list of records).
There are many approaches to fulfil your specific needs, but being able to call a custom javascript function from a button should be a good starting point, the rest is simply the knowledge of CRM SDK, so how to create an entity using API or open a form or open a web resource - everything is very well documented and you can get it simply by asking google, so I will not post any blog here, not to advertise too much. Also I's suggest downloading latest CRM SDK (https://www.microsoft.com/en-us/download/details.aspx?id=50032) - you have many sample code there, regarding plugins and some form modifications, you should also check this out.
To make it easier for you, you should refer to this "menu" as "Command bar" or "Ribbon", so rather look for "adding custom button to command bar CRM 2016" and you will be all good. Also to make a form for choosing a template, you will probably need some custom web resource, so "creating custom html5 web resource CRM 2016" should give you some good examples.