We have a 24/7 operation, with two 2821s with VWIC-2MFT-T1s acting as Voice Gateways. Each has an multiple ISDN PRIs to the Telco that are used for incoming and outbound calls.
My question is if a Gateway has to be taken down for maintenance, is it possible to refuse incoming calls from the Telco while preserving existing calls?
Obviously this can be done on the Telco's end, but I'm wondering if it's possible to do without them getting involved. The gateways currently run MGCP but I'm converting them over to H.323 next month.