I have a network with 192.168.1.0(VLAN1) and 172.16.1.0(VLAN10).

The 172 is a VOIP system and the 192 is client computers. There is a small issue with routing from 192 to 172. There is a web interface on the VOIP phones that allows them to be configured.

I can ping from 172 to 192, but not back the other way.

There is a CISCO router and a switch. The router has gateway for 192 (say 192.168.1.99) and 172(say 172.16.1.99). A ping from 172 to 192 is successful. Traceroute shows it going from the 172.16.1.99 gateway to the 192.168.1.200 destination IP.

A ping from 192.167.1.227 to 172.16.1.200 fails except for 2 IP's the gateway and the dhcp are successful. The failure stops at the 192 gateway.

Why would some work and others not?

Well two angles... 1) ACL's under IOS, and 2) default gateways on the clients...?

Indeed. The default gateway on the dhcp to the clients (in this case the phones)

Thanks