On which platform is it easier to make your own CRM?

Question

CRM

In general, there are many different and wonderful CRMs on the market, but each of them lacks something. And the question arose of creating our own database with the necessary functionality for sales, clear filtering, logistics, call center, differentiation of rights, logging of someone who did something, SMS notifications, mailing lists, integration with several more useful services.
So, in the absence of even superficial knowledge, who should implement it on what and how, I would like to ask:
1. Does it make sense to do from scratch or finish the most suitable CRM available?
2. Maybe there is some type of constructor?
3. Or which engine is the easiest to adapt to your needs?
4. Where is the best place to contact on this issue?

Answer 1

Many CRMs exist for many needs, and serious CRMs are tailored to the requirements of each individual company, because there is no universal one that will suit everyone and you cannot create it. More precisely, you can mislead yourself that you created it, but then you will still have to adjust it to the client's business processes.

Answer 2

1. There is no
point 2. Here, the other day, the source code of Yandex was discussed. Funny :)
3. Here you need a framework. A bunch of Yii + ExtJS for example
4. To Google.