1.9 Overlapping and Nonconsecutive Numbers

This topic describes overlapping and nonconsecutive numbers.

The figure illustrates a deployment with overlapping and nonconsecutive numbers.

In the example, IP phones at the main site use directory numbers 1001 to 1099, 2000 to 2157, and 2365 to 2999. At the remote site, 1001 to 1099 and 2158 to 2364 are used. There are two issues with these directory numbers: 1001 to 1099 overlap, and these directory numbers exist at both sites, so they are not unique throughout the complete deployment. In addition, the nonconsecutive use of the range 2000 to 2999 (some numbers out of this range are used at the remote site, and the others are used at the main site) would require many entries in call-routing tables because the ranges cannot be summarized by one (or a few) entries.