How to get a user's session-id

Hi,
I want to get session-id of a registered user. I am able to get this id for the user which is connected via LAN using ChanIsAvail.

ChanIsAvail(SIP/abc)

this returns available users name with session-id like SIP/abc-094f90e

but when i do following

ChanIsAvail(SIP/abc@119.157.35.2:5060) then following error is shown on asterisk cli.

-- Executing [s@macro-custdial:154] ChanIsAvail("OSS/dsp", "SIP/abc@119.157.35.2:5060") in new stack

[Oct 5 12:48:07] WARNING[17067]: chan_sip.c:2753 create_addr: No such host: 119.157.35.2

can anyone help me out how can i accomplish it?