I gave up on this for sometime but i finally managed to upgrade and i am glad to share the procedure here for all those who are looking to do same thing but finds its difficult..its not a commonly used device but very handy at times...
In the begining i was trying to upgrade ata sccp 3.1.0 to sip 3.2 and it never worked so after doing a lot of reading and searching through forums i thought about using a lower version and it paid off.
Procedure:
I had my ATA 186 (sccp ) connected on my internal home network on netgear wireless router so it was on internal dhcp server to get the ip address, my laptop was also connected on same network. First thing i had to do was access ata through web http://x.x.x.x/dev where x.x.x.x is ip address of ATA.
next you have to create a ata configuration file using procedure explained below
http://www.cisco.com/univercd/cc/td/doc/product/voice/ata/ataadmn/sccp3_0/sccpach3.htm#wp1107755
here is out put from a sample config file, note that the parameter upgrade code is very important as it tells the ATA about firmware
#txt
UIPassword:0
UseTftp:1
TftpURL:192.168.1.10
EncryptKey:0
upgradecode:3,0x301,0x0400,0x0200,192.168.1.8,69,0x050616a,ATA030201SIP050616A.zup
upgradelang:0,0x301,0x0400,0x0200,0.0.0.0,69,0,none
Dhcp:1
StaticIp:0
StaticRoute:0
StaticNetMask:0
DNS1IP:0.0.0.0
DNS2IP:0.0.0.0
VLANSetting:0x0000002b
CA0orCM0:0
CA1orCM1:0
CA0UID:0
CA1UID:0
EPID0orSID0:.
EPID1orSID1:.
PrfCodec:1
LBRCodec:3
MediaPort:16384
Domain:0
AudioMode:0x00350035
NumTxFrames:2
CallerIdMethod:0x00019e60
Polarity:0
FXSInputLevel:-1
FXSOutputLevel:-4
ConnectMode:0x90000400
SigTimer:0x00000064
OpFlags:0x2
TOS:0xA0
DialTone:2,31538,30831,1380,1740,1,0,0,1000
DialTone2:2,29780,30743,1252,1384,1,0,0,1000
BusyTone:2,30467,28959,1191,1513,0,4000,4000,0
ReorderTone:2,30467,28959,1191,1513,0,2000,2000,0
RingBackTone:2,30831,30467,1943,2111,0,16000,32000,0
CallWaitTone:1,30831,0,5493,0,0,2400,2400,4800
AlertTone:1,30467,0,5970,0,0,480,480,1920
NPrintf:0
TraceFlags:0x00000000
SyslogIP:0.0.0.0.514
SyslogCtrl:0x00000000
next you will have to run cfgmft tool to generate binaray files. Here is the procedure to do this
http://www.cisco.com/univercd/cc/td/doc/product/voice/ata/ataadmn/sccp3_0/sccpach3.htm#wp1107755
replace sccp with sip in the command.
