Returns true if the user is a member of the community group. 

This method can be accessed through the CommunityGroup.asmx file located in:

~/Workarea/webservices/WebServiceAPI/Community/CommunityGroup.asmx

[SoapHeader("AuthHeader")]
[SoapHeader("RequestInfoHeader")]
[WebMethod(MessageName = "IsUserInCommunityGroup", Description = "Returns true if the  user is a member of the community group.")]
public bool IsUserInCommunityGroup(long communityGroupId, long userId);

<SoapHeader("AuthHeader")>
<SoapHeader("RequestInfoHeader")>
<WebMethod(MessageName = "IsUserInCommunityGroup", Description = "Returns true if the  user is a member of the community group.")>
Public Function IsUserInCommunityGroup(communityGroupId As long, userId As long) As bool