If you do the mistake of writing in the wrong URL during setup or forget to do it, here is a guide of how to change it, so that content download and livemeeting works externally.
Error message when you try to use the Live Meeting console to connect to Communications Server 2007: "Live Meeting cannot connect to the meeting."
To configure the external Web farm FQDN, follow these steps:
1.
Log on to the computer that is running Communications Server 2007 Standard Edition or Communications Server 2007 Enterprise edition by using an account that is a member of the RTCUniversalServerAdmins group or that has equivalent permissions.
2.
Click Start, click Run, type wbemtest, and then click OK.
3.
In the Windows Management Instrumentation Tester dialog box, click Connect.
4.
In the Connect dialog box, type root\cimv2 in the Namespace box, and then click Connect.
5.
In the Windows Management Instrumentation Tester dialog box, click Query.
6.
In the Query dialog box, type the following in the Enter Query box according to the edition of Communications Server 2007 that you are using, and then click Apply:
For Communications Server 2007 Enterprise pool
Select * from MSFT_SIPGroupExpansionSetting where backend="server name\\sql instance"
For Communications Server 2007 Standard Edition
Select * from MSFT_SIPGroupExpansionSetting where backend="(local)\\rtc"
7.
In the Query Result dialog box, double-click the result.
8.
Select ExternalDLExpansionWebURL, and then click Edit Property.
9.
In the Property Editor dialog box, click to select the Not NULL option.
10.
In the Value box, type the external Web farm URL in the following format, and then click Save Property:
https://externalurl.domain.com/GroupExpansion/service.asmx
11.
Click Close two times.
12.
In the Windows Management Instrumentation Tester dialog box, click Query.
13.
In the Query dialog box, type the following in the Enter Query box according to the edition of Communications Server 2007 that you are using, and then click Apply:
For Communications Server 2007 Enterprise pool
Select * from MSFT_SIPDataMCUCapabilitySetting where backend="server name\\sql instance"
For Communications Server 2007 Standard Edition
Select * from MSFT_SIPDataMCUCapabilitySetting where backend="(local)\\rtc"
14.
In the Query Result dialog box, double-click the result.
15.
Select ExternalClientContentDownloadURL, and then click Edit Property.
16.
In the Property Editor dialog box, click to select the Not NULL option.
17.
In the Value box, type the external Web farm URL in the following format, and then click Save Property:
https://externalurl.domain.com/etc/place/null
18.
Click Close two times.
19.
In the Windows Management Instrumentation Tester dialog box, click Query.
20.
In the Query dialog box, type the following in the Enter Query box according to the edition of Communications Server 2007 that you are using, and then click Apply:
For Communications Server 2007 Enterprise pool
Select * from MSFT_SIPAddressBookSetting where backend="server name\\sql instance"
For Communications Server 2007 Standard Edition
Select * from MSFT_SIPAddressBookSetting where backend="(local)\\rtc"
21.
In the Query Result dialog box, double-click the result.
22.
Select ExternalURL, and then click Edit Property.
23.
In the Property Editor dialog box, click to select the Not NULL option.
24.
In the Value box, type the external Web farm URL in the following format, and then click Save Property:
https://externalurl.domain.com/abs/Ext
25.
Click Close two times.
26.
Click Exit.
source
http://support.microsoft.com/kb/938288
If you receive an error in wbemtest saying “error code 0x800407d0” make sure that the account is a member of RTCUniversalServerAdmins