Cisco IP Phone to another Cisco IP Phone
Cisco does not
support connecting an IP phone to another IP Phone through the PC port. Each IP
Phone should connect directly to a switch port. If phones are connected
together in a line by using the PC port, the phones do not work.
broadcast storms cause IP phones to reset, or be unable to make or answer a
Layer 2 broadcast storm (lasting several minutes) on the voice VLAN may cause
IP phones to reset, lose an active call, or be unable to initiate or answer a
call. Phones may not come up until a broadcast storm ends.
network connection from the phone to a workstation
If you power
your phone through the network connection, you must be careful if you decide to
unplug the network connection of the phone and plug the cable into a desktop
card in the computer cannot receive power through the network connection; if
power comes through the connection, the network card can be destroyed. To
protect a network card, wait 10 seconds or longer after unplugging the cable
from the phone before plugging it into a computer. This delay gives the switch
enough time to recognize that there is no longer a phone on the line and to
stop providing power to the cable.
the network configuration options are locked to prevent users from making
changes that could impact their network connectivity. You must unlock the
network configuration options before you can configure them. See
Apply a Phone Password for details.
administrator password is not set in common phone profile, then user can modify
the network settings.
between the phone and another device
The RxType and
the TxType statistics show the codec that is used for a conversation between
this Cisco IP Phone and the other device. The values of these statistics should
match. If they do not, verify that the other device can handle the codec
conversation, or that a transcoder is in place to handle the service.
mismatch between the phone and another device
The RxSize and
the TxSize statistics show the size of the voice packets that are used in a
conversation between this Cisco IP Phone and the other device. The values of
these statistics should match.
condition can occur when the following conditions are met:
- The SW Port Configuration
option in the Network Configuration menu on the phone is set to 10 Half
- The phone receives power
from an external power supply.
- The phone is powered down
(the power supply is disconnected).
In this case,
the switch port on the phone can become disabled and the following message
appears in the switch console log:
this problem, reenable the port from the switch.