Concurrently, the Somali Transitional Federal Government began preparations to revive the national postal service. The government's overall reconstruction plan for Somali Post is structured into three Phases spread out over a period of ten years. Phase I will see the reconstruction of the postal headquarters and General Post Office (GPO), as well as the establishment of 16 branch offices in the capital and 17 in regional bases. As of March 2012, the Somali authorities have re-established Somalia's membership with the Universal Postal Union (UPU), and taken part once again in the Union's affairs. They have also rehabilitated the GPO in Mogadishu, and appointed an official Postal Consultant to provide professional advice on the renovations. Phase II of the rehabilitation project involves the construction of 718 postal outlets from 2014 to 2016. Phase III is slated to begin in 2017, with the objective of creating 897 postal outlets by 2022.
Try to answer this question if possible (otherwise reply "unanswerable"): When did Somalia first join the UPU?
unanswerable