T1 with an ISDN circuit to handle burst - is that possible

[lohmannt]

I have a T1 that will hit 85%-95% usage in the near future. Rather than paying for a 2nd T1 and load balancing between the two - is there a way to configure a dial-on-demand situation so when the T1 needs to burst above 100% it spills over to the ISDN circuit saving us money?

[thisisshanky · Accepted solution]

Yes, you could use the backup interface command use the isdn int. as backup int. for the T1 interface. You can specify a backup threshold to kick off the ISDN line. Check this link

http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_configuration_guide_chapter09186a0080087225.html