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SDP mangling in private network

Jan 19, 2010 at 1:26 PM

Hi, we are testing SIPSorcery as proxy and registrar on a private network, i.e. the IP addresses start with 10. On this network we have several sub nets with a number of user agents in each sub net. When calling from one UA to another, even when they are on the same sub net, the SDP appears to get mangled and mangled incorrectly. It appears as if "OK" responses to "INVITE" requests contain an incorrect SDP "c=" line - informing the calling UA to send RTP traffic to itself rather than the called UA.

Could this be caused by an incorrect configuration on our part?

Is there a way to completely disable SDP mangling in the configuration?


Jan 19, 2010 at 10:49 PM

The application server will mangle SDP by default since in the majority of situations it is required. There are two approaches to disabling SDP mangling on a call leg:

1. Set SIP accounts on the same private LAN with the same networkid. The application server will not manlge SDP when it detects a call between SIP accounts with the same networkid. The networkid can be any arbitrary string but needs to be the same for all SIP accounts that require un-mangled calls between them. For example I have the networkid on all the SIP accounts for the phones on my network set to "home",

2. A more granular approach is to turn mangling off in the dialplan by using the [ma=false], where ma stands for mangling, option on an individual call leg, for example:



Jan 25, 2010 at 3:19 PM

Thanks. The dial plan option seems to work fine.