CiSCO CME calls issue

I have a big problem with Cisco voip configuration. I have two CME router which is connected by IPsec over gre tunnel vpn. The flow between router Irak and router CI is correct but we can not make any calls, we heard a busy tone. However the calls between Router CI and Router Irak work well.
I don't know how to fix this issue. I need your help please.

Best Regards,
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You are no natting the SIP traffic on the CI router ( disabling SIP-ALG). I would do the same on the Irak router. This is a common issue.

no ip nat service sip tcp port 5060
no ip nat service sip udp port 5060
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