Need guidance on building a Unified Communications/Messaging system?

Question

Work organization

Given:
A small company that has a staff of developers (Linux) and managers (Windows). The following are used for communication: SIP-telephony (hardphones, softphones), corporate Skype, ICQ, E-mail (Google Apps and just on gmail.com).
The main problems:
- There is no single history of communication when working with a client
- There is no possibility for the client to transfer it transparently to another manager
- In the event of any problem, there is no way to quickly transfer the already accumulated information on the problem from the manager to the developer
What we want to get
+ Flexible customizable system: minimum - unified messages (Unified Messaging), maximum - unified communications (Unified Communications)
+ It is highly desirable to deploy a system based on free software (Linux)
+ If the system is commercial - its cost should be within a reasonable framework (about $ 1000 in total for 25 users)
+ The solution should not be SaaS - everything will be hosted on its own servers
I ask for recommendations on:
1 ) existing systems of this kind
2) if similar systems that meet my requirements are unknown to you, please provide components that can be used to assemble this system “in parts”

Answer 1

For quick communication, he transferred everyone to corporate Skype accounts, corporate mail for the domain from Google, + it has aliases, groups and other goodies for collaboration, the whole life of the company is in the megaplan.
I don’t know what you are afraid of so saas then?