Trouble Accessing Schema-Qualified Table

Hello,

I need to access a database using two different schemas. During initialization the default schema is set as follows:

set schema 'ucm';

Then later, I need to get data from a table in another schema 'ts_sofia_internal', so I tried the following, but it returns an error as shown:

teo=# select * from sip_presence('ts_sofia_internal') where sip_presence.sip_user='1003';
ERROR: function sip_presence(unknown) does not exist
LINE 1: select * from sip_presence('ts_sofia_internal') where sip_pr...
^
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
teo=#

Does anyone know how I can do this? By the way, I'm using odbc to connect to the database.

Thanks,
Jerry