IP phone can not register after switch reload

[tianwen.zhao]

Hello everyone,

    After our switch reload ,all of the ip phone can not dial, but the ip phone can get an ip address and tftp server.but they just can not register with the call manager...and I don't know why.

Here are my configuration:

!
ip dhcp pool Voice
network 172.28.0.0 255.255.0.0
default-router 172.28.15.254
option 150 ip 172.21.15.232 172.21.15.231
dns-server 10.64.0.101 10.176.0.101
!

SW254#sho ip dhcp binding
Bindings from all pools not associated with VRF:
IP address Client-ID/ Lease expiration Type
Hardware address/
User name
172.28.0.79 019c.57ad.b584.c4 Feb 12 2019 10:39 AM Automatic
172.28.0.80 01dc.cec1.d539.02 Feb 12 2019 10:44 AM Automatic
!
SW254#ping 172.21.15.231

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.21.15.231, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/11/17 ms

Thank you

[HARIS_HUSSAIN · Accepted solution]

Look for ACLs if they are blocking Subnet A. You must add option 150 as the IP Phone if they cannot find Option 150 will use the one which is stored in buffer from previous registration. So if you have new phone or reset existing phone you cannot register

AND ** PLEASE DON'T FORGET TO RATE AND ACCEPT SOLUTION IF APPLICABLE

Thanks,
Haris

[tianwen.zhao]

Finally, we found the reason why the ip phone can not register

there is two traffice flow paths:
from ip phone to CUCM(outside route):
IPPHone-----Switch-----VOICE GATEWAY------ROUTER-------OSPF1----------ROUTER----CUCM

from CUCM phone to ip phone(return route):
CUCM----ROUTER----OSPF2------ROUTER-------VOICE GATEWAY------Switch----IPPHone

because outside route and return route isn't the same route.
It returned to normal after we changed the route to the same one

Thank you HARIS