The selection of a general purpose radio technology such as LTE for public safety networks has the aim of addressing the classical problems from LMR systems, that result not only in expensive equipment but also very limited innovation capabilities when compared with the bustling Internet ecosystem and the new possibilities of new broadband cell networks and smartphones. The unanimous agreement by the sector towards LTE was only the first step; driven by most of the relevant stakeholders’ involvement, the 3GPP defined a complete suite of full-IP standards for providing MC-Voice. The resulting Rel’13 (and beyond) MCPTT communications puzzle comprises an impressive set of different technologies as follows: brand-new MC-grade Rel’13 compatible LTE access network including eMBMS capabilities and high priority QCIs, SIP/IMS Core, PCRF and BM-SC for QPP and multicast, and MCPTT application and configuration and support servers on the network side; similarly eMBMS and MCPTT set of protocols on the UE side. Building such a complex system demands the bringing together of different stakeholders with opposing interests even for development, research or testing purposes, and it is only affordable for a very limited set of key players in the world. Even the industry itself has acknowledged that this situation increases the time-to-market and results in duplicated no-added-value efforts. Thus, regardless of the apparent openness of the MCPTT standardized ecosystem, the resulting heterogeneity brings in practice new entry barriers, jeopardizes the involvement of new players, threatens the role of former OTT PTT solutions providers and local integrators –in comparison with big vendors- and reduces innovation possibilities. It questions the overall initial aim behind open standardized technology. This collaborative project aims at facing the new challenges of a complex ecosystem through the definition, development and validation of a MCPTT UE Open Platform (MCOP) that identifies neat interfaces between the different technologies in the UEs, reduces the integration efforts and removes the entry barriers.