The 3CX installed base and community is growing rapidly and with that the demand for 3rd party applications and solutions for 3CX Phone System . To accommodate this demand, we have launched a 3rd party solutions page which lists Add ons available for 3CX Phone System. The add ons range from integration modules for CRM systems to Voice applications developed with the 3CX Voice Application Designer. Currently, solutions from Bortech , Deerfield , InfoSys ,  MDL solutions and SWS are featured. Partners interested to develop add on applications for 3CX Phone System should review the 3CX APIs available here . For integration with CRM solutions, we recommend using the CRM plug in API – since you can re-use our C# code, and you just need to adapt the “CRM calls” with the calls of the CRM package you wish to support.  If you have a project or solution that you wish to integrate with and require help in using these APIs, contact your channel manager for more information

Continued here:
3CX Application Exchange – 3rd Party application solutions page