Cisco do not recommend the use of Gigastack GBIC's when transporting IPT. You should think about star wiring to a 3508. See this note.http://www.cisco.com/univercd/cc/td/doc/product/voice/ip_tele/avvidqos/qoscamps.htm#xtocid269428
Echo Daves suggestion that you post this on the Contact Centre List.However, Gateways in IPCC are not the same things as gateways in VoIP/IPT. These are Peripheral Gateways.For the size of CallCentre you have here, it might be worth looking at Cisco'...