Can you confirm whether you are using the latest version of jabber for iPhone which is 9.6; if thats the case from jabber for iPhone version 9.5 and onwards; we need to do special configuration in jabber for iPhone; you may want to refer to the following link for more information;
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/jabber/iPhone_iPad/JABI_BK_I30346C6_00_installation-and-configuration-guide-for-iOS/JABI_BK_I30346C6_00_installation-and-configuration-guide-for-iOS_chapter_0111.html#CJAB_RF_D49B9A31_00
If you are already using a jabber-config.xml for jabber for windows; we still will use the same file and just add the following extra (sample) portion of config to the same file;
< Directory>
<DirectoryServerType>BDI</DirectoryServerType>
<BDIPrimaryServerName>x.x.x.x</BDIPrimaryServerName>
<BDIPresenceDomain>test.com</BDIPresenceDomain>
<BDISearchBase1>DC=test,DC=com</BDISearchBase1>
<BDIUseJabberCredentials>True</BDIUseJabberCredentials>
</Directory>
Note the values above are coming from a test lab node; though you will need to know what the same would be in your case and try attempt a file edit accordingly.
-hth