Assume that a user (user A) installs Microsoft Office 2013 Service Pack 1 (SP1) on a Lync 2013 client. Then, user A tries to send a file to another user (user B) in a Persistent Chat room by using the client. In this situation, user A may encounter the following issues:
If user A is an external user and user B is an internal user, user A cannot send the file. Additionally, user A will receive error ID 70.
If user A is an internal user and user B is an external user, user A cannot send the file. Additionally, user A will receive the following error message:
error in transfer
This issue occurs because the Persistent Chat server does not provide the external web services URL.
To work around this issue, you must publish an A record to point to the public IP address of the router on the external Domain Name System (DNS) side. The router port must be forwarded to the external IP of Threat Management Gateway.
Note This workaround does not apply to all environments. For example, the internal DNS name may not be publishable in external DNS in some environments.
For more information about how to determine DNS requirements, go to the following Microsoft website: