The best way forward is to trade in the perpetual license for an annual license. It is free for the first year. Plus in comparison to other software offering similar value, the price point of 3CX is unbeatable!
By not renewing your customers' maintenance they lose access to the following updates: IP Phone firmware, SIP Trunk Providers, CRM, Video, new features, and our SMTP, FQDN, SSL Certification Services. Let's not forget the Ios and Android Clients. They lose key features.
They will not be able to upgrade so they will be on an unsupported version - If they have issues, we cannot help out.
And lastly, the security updates - therefore you put your customers at risk! Surely as a Partner, this should be important to you?
As we give you 1 year free once you trade-in, plus all the above benefits, you should renew thereafter as an annual subscription.