TEI values are used to identify terminating equipment, mostly in a point-to-multipoint setup, since they "bus" may extend to a number of devices. However, in a point-to-point setup, the TEI value is statically set, often to "0".
Recently when testing a BRA cell router we spent ages in trying to get outgoing calls working. Most cell routers are point-to-point, and thus the TEI value for each link is "0". This cell router, though, has a point-to-multipoint architecture. As a result, we had to remove the static TEI value from the link's properties. Immediately the link was assigned a TEI value dynamically by the router (as seen under the Link Supervisor) and calls worked.
So if the protocol is correct (ETSI, etc) and the correct termination is setup (Q,S or T), then any link problems could be TEI value related.
