Both Tigo and Personal deny any wrongdoing on their side and blame the now Facebook owned company for their unavailability.
Users started complaining about the difficulty of making calls from Whatsapp prompting the CONATEL (The local telecommunications regulator) to investigate the issue. CONATEL will issue a press release tomorrow about this issue.
This new scandal comes at the same time that CONATEL is calling for public consultations about the overhaul of the telecommunications bill that will impact services under its supervision.
http://www.conatel.gov.py/index.php?option=com_content&view=article&id=667:conatel-inicia-proceso-de-consulta-publica-sobre-modificacion-de-ley-de-telecomunicaciones&catid=31&Itemid=101
Several media outlets are already publishing stories about the blocking:
http://www.abc.com.py/nacionales/conatel-advierte-a-operadoras-sobre-llamadas-por-whatsapp-1351966.html
http://www.ultimahora.com/whatsapp-conatel-se-pronunciara-supuestos-bloqueos-llamadas-n884117.html
http://www.hoy.com.py/nacionales/conatel-operadoras-no-pueden-bloquear-llamadas-por-whatsapp
http://www.extra.com.py/denuncia/denuncian-bloqueo-de-llamadas-por-whatsapp.html
http://www.noticiasdeamambay.com/llamar-via-whatsapp-es-mas-barato-y-dos-empresas-lo-bloquearon-afirman/