I've not seen an integration for this CRM, but we are currently engaged with building 3 different CRM integrations at the moment. If you need some help, we can offer some advice on the process and some of the pitfalls to watch out for.
You can create the integration yourself by using this tool: https://www.3cx.com/docs/crm-integration/
just wondering what sort of skill level is required for the integration i.e. will I need a developer?