The Windows client allows you to call a SIP Call-ID (eg email@example.com) when you configure the SIP Call-ID in the phone number field in the phonebook. Android version 1.2.9 converts the alpha numeric SIP Call-ID to just numbers, if you select that contact's SIP Call-ID from the contact list. The call then fails. If you manually enter the SIP Call-ID in Android no conversion happens but the call also fails. Both the Windows and Android clients are running using WI-FI behind the same NAT router and both use STUN to sucessfully dial and receive calls to/from mobile, fixed line and DID numbers, it is just the SIP Call-ID processing that is missing from the Android version. Is this likely to be fixed in the next version? Need to make a decision on both the Windows and Android clients that we roll out.