How to enable blocked SIP Providers
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The SIP protocol is used heavily for attacks from the Internet. OpenScape Office V3.2 and HiPath 3000 V9 have implemented blocking of unknown peers to prevent unautorized access.
ITSP communication is only possible with IP addresses and ports known to the system. If several servers are used by the ITSP they have to be communicated via DNS-SRV to the SEN platform. If this is not done by the provider a workaround described in the following document may be used.
The document gives a description of all protection mechanisms, diagostic data and recommended measures as well.