Telnet disconnects on handheld device AIX

I have intermec handheld device which is connecting to AIX Server on port 12431 or whatever. ( oracle application )

The handheld device connects for few seconds and then disconnects from the AIX server. Once it disconnects the handheld device automatically switches off.

Are there any parameters which I have to set so that Telnet doesn't disconnect or re-connect right away. such tcp keepalive or something like that ?

How do I set it up ?

Note: When I try the same thing from laptop connecting to the server
telnet 10.11.111.110 12431
then it doesn't disconnect. it works fine.

anyone ?

Add TMOUT=0 to your environment variable.

I did that. TMOUT=0 but still doesn't work

checked the security parameter and changed that one also doesn't work either...

is there a parameter called TCP KEEP ALIVE ?

please note: the handheld device works fine in the same environment with HP-UNIX servers but doesn't work with AIX