Cisco CP-7910G IP phones issue on HP 1920 PoE+ switch

[evolotas1]

Dear all,

we are dealing with a strange issue. We have a number of old Cisco IP phones CP-7910G and we connect them on a new HP 1920 24 port Gigabit PoE+ switch. It appears that the phones do not turn on.

When adding those specific IP Phones on a Cisco Catalyst PoE switch, phones turn on and operate normally.

at the sametime when adding other PoE devices on the HP 1920 24G PoE, just like Access points etc it seems that they get power and they operate normally.

Do you have any ideas what might cause the issue specifically with the Cisco 7910G on the HP switch? 

Thank you in advance.

Regards

[Mark Malone]

some cisco devices support cisco inline power only (proprietary) and will only work with Cisco devices

some are open standard use 802.3af PoE and 802.3at PoE+ I would check exactly what that device is capable of in terms of power inline

[evolotas1]

Thank you

[Mohammed al Baqari]

Hi,

Cisco  7910 uses cisco prestandard for getting power. They don't understand 802.3af. Therefore you won't be able to power them using a switch which doesn't support prestandard.

One thing you can do is to disable PoE+ and configure static power on the ports (I don't know how to do it on HP switches). This way the phones can get the max power (or whatever you configure) without going in PoE negotiation.

[evolotas1]

Thank you very much!!

[jamesholub]

Try the power pre-std-detect command on the HP switch.  I don't know if the 1920's support pre-standard but it worked for me on the HP 5400zl and 2920 models.