SUA: GTT function placement

Hi all,

In the SUA draft the GT Translation function is positioned in the "SG as relay-point". This is clear for
inbound messages coming from the SS7 network with "route on GT" in their called address. 

For outbound messages (from AS/ASP to SS7) it might be possible to perform the GTT either in the SG or in the
ASP. In a multiple SG's configuration, it seems that GTT is required in the ASP to perform SG selection; if
the ASP is connected to multiple SG's; the ASP can store the availability of remote PC/SSN thru each SG, and
then use this information to perform SG selection. For outbound messages with "route on GT" in the called
address, the ASP must perform the GTT to derive a PC, and then select a SG capable to reach that PC. 

If the ASP performs a GTT on outbound messages, it would be nice to add the derived PC into the SUA message
called address, and then the SGP uses that PC for the MTP3 DPC. Can we assume that a SGP receiving a message
from an ASP with a called address containing [RI="route on GT" , a GT, and a PC] will not perform its own GTT
and will use that DPC value for the MTP3 header ?

Do you foresee any other issues or advantages to do the GTT in the ASP as well ?

Marc Lamberton
Compaq TPU
marc.lamberton <at> compaq.com
Tel. (33)4 9295 5598