CCA and ISO
The two that I hear most about are the CCA and ISO accreditations
CCA Global Standard is an independent assessment and endorsement of an organisation's customer service operation.
The Standard is designed by industry, for industry and assesses the documented process, implementation and development of the customer service operation. It will align customer experience strategy to the vision, values and purposes of the organisation, identify talent capability, assess ease of access and channel strategy and enable accredited organisations to display the CCA Accredited Member recognition mark.
ISO 18295-1:2017 specifies service requirements for customer contact centres (CCC). It specifies a framework for any CCC that aims to assist in providing clients and customers with services that continuously and proactively meet or exceed their needs.
ISO 18295-1:2017 is applicable to both in-house (captive) and outsourced (third party operator) CCCs of all sizes, across all sectors and all interaction channels, including inbound and outbound. It specifies performance metrics (KPIs) as and where required.