Referred documentation where arrays are mandatory:

http://support.sippysoft.com/solution/articles/107508-packet-sniffer-scheduler


<member><name>target_hosts</name>
<value><array><data>
<value><string>1.2.3.4</string></value>
<value><string>2.2.2.2</string></value>
</data></array></value></member>


Full request:

<?xml version="1.0"?>
<methodCall><methodName>dumpIPTraffic</methodName>
<params> <param> <value><struct>
<member><name>i_customer</name><value><int>1</int></value></member>
<member><name>email</name><value><string>noreply@sippysoft.com</string></value></member>
<member><name>period</name><value><int>1</int></value></member>
<member><name>interface</name><value><string>igb1</string></value></member>
<member><name>target_hosts</name>
<value><array><data>
<value><string>1.2.3.4</string></value>
<value><string>2.2.2.2</string></value>
</data></array></value>
</member>
</struct></value> </param> </params> 
</methodCall>