Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

Delay in Receiving Dial Tone

Anyone having any issues w/ the 7910 phones not giving a dial tone as soon as the handset is picked up.?

Seems our 7960's function fine, but the 7910's will intermittently not give a dial tone when the handset is picked up for sometimes up to 6 seconds.

When this happens its the users instinct to repeatedly hit the on hook/off hook button on the phone.... This only delays receiving the dial tone.

I'm concerned in the event of an emergency.... when no dial tone is detected the user will panic.... and make the situation worse.

Any help or suggestions appreciated.

New Member

Re: Delay in Receiving Dial Tone


since the callmanager instructs the phone to play the dialtone, maybe there is some sort of network congestion ? have the 7910's been installed into the same vlan / ip-network as the 7960's ?

we had this problem once, when the callmanager-cpu was peaked to 100% because of low memory and heavy paging activity. but it concerned ALL phones , not just a part of them.

i suggest :

- check your callmanagers cpu usage

- check vlans / routing

greetings, gerhard


Re: Delay in Receiving Dial Tone


Have not seen that myself but anyway....

CSCdt28640 Bug Details

Symptom: 7960/7940/7910 phone users may experience a delay between the time they go off-hook and

the time they hear dialtone on their phone. This delay can be anywhere between

3 - 30 seconds.

Condition: Problem is seen when the CallManager and phones are on the same broadcast

domain. The problem is more pronounced when the ARP cache timeout sent by the

DHCP server is very short. (e.g. 60 seconds)

Workaround: Move the CallManager to a separate IP Subnet/VLAN/Broadcast Domain.

Workaround 2: There is a known issue with the Cisco Network Registrar DHCP server. The

server defaults the ARP cache timeout to 60 seconds when the option is not

configured. This causes the phones to clear their ARP caches every 60

seconds. This can aggravate the problem. Have the administrator configure

the ARP cache timeout option to something reasonable for the network. For

example, the phone will default to 40 minutes when no option is received.

Workaround 3: The issue has been resolved in the following loads,

P003T301, P004T301, P00303010102, P00403010102,P002C301 and P001C301

New Member

Re: Delay in Receiving Dial Tone

In Workaround 3, do you know which phone load relates to the 7910's..

The latest on cisco is P00403020215, which I've installed, but that doesn't fix the problem.

I've opened a tac case, because Workaround 1 seems pretty intense, and workaround 2 doesnt' make sense... unless I'm reading it wrong.



Cisco Employee

Re: Delay in Receiving Dial Tone

I would suggest you look at the CCM trace and determine the points where the phone goes off-hook and where CCM tells the phone to play InsideDialTone.

Even better would be a sniffer trace taken at the phone.

CreatePlease to create content