SIP TRUNK with UC540 and VCS Expressway

[jesusdavilan]

I am trying to configure a SIP trunk in a UC540 to a VCS Expressway, using CCA, but I do not manage to have SIP trunk UP. Does anyone knows a trick to make this work. Or do I have make the configuration via CLI?                  

[jesusdavilan]

Team,

I managed to create a SIP trunk between a UC540 and VCS Expressway. I could call from an E20 (registered in the VCS) to a SPA525G2 registered in the UC540) back and forward.

However, after sometime, the SIP trunk became unstable. The trunk is flapping.  I only can make call if I change the configuration in Security (i.e. enable or disable the loopback fastethernet).

But here comes the tricky part.  If I do "apply" the modification to the config, but I do not give the OK to save the config the SIP trunk works and calls can be done.

However, if I modified the configuration, "apply" and then "OK" to save the config, the SIP trunk does not work.

I have been dealing with this the whole day, but I wonder if there is a bug in the IOS. I am using IOS 15.2(2)