Saturday, March 27, 2010


Hi Guys,

Just doing my study for my CCIE Voice and I came across something that always kinda caused me issues, and I thought i would share

Right now i am studying SIP, and it is talking about DTMF-Relay.

To cut a long story short: DTMF-Relay for SIP dial-peers is RTPE-NTE, RTP-NTE is in-band signalling, meaning it is part of the RTP stream, the problem is that SCCP Phones don't understand RTP-NTE! So they cannot send or receive the DTMF tones correctly.

The way to resolve this is to either:

1. Run an MTP and enable this for the trunk for CUCM (this is your only option in CUCM 4)
2. Change the dtmf-relay method on the dial-peer using

#dial-peer voice 999 voip

Now, the thing is, when i tried thsi with my SIP provider it failed miserably, that is because the SIP provider is expecting the digits as SIP-NOTIFY, the cisco routers have a solution to this too..

for gateways running CCME with SIP trunks, you need to configure RTP-NTE. This will convert the signalling received from the SCCP phones to Named Telephony Event (Which is an RFC supported by most SIP providers.)

Here is some more info i found:

The last blog entry covered DTMF relay. This blog entry will focus on Cisco IP Phone and Cisco SIP Trunk DTMF relay support. Cisco’s first generation of IP phones do not support RFC2833 DTMF-Relay. All digits are sent out of band in either SCCP or SIP signaling packets depending on the phone load. Cisco first generation phones are referred to as Type A phones in the Cisco Unified Communications Manager 6.x SRND (Solution Reference Network Design) guide available at Type A phones include the following phones:

• 7902
• 7905
• 7910
• 7912
• 7940
• 7960

Cisco’s second generation phones support RFC2833 DTMF Relay when registered with Cisco Unified Call Manager versions 5.0 and later. These phones include the following:

• 7906
• 7911
• 7941
• 7942
• 7945
• 7961
• 7962
• 7965
• 7970
• 7971
• 7975


Thursday, March 18, 2010

Cisco excites the market with new Switch announcement

Cisco have just announced three new switches:

  • Catalyst 3560-X
  • Catalyst 3750-X
  • Catalyst 2960-S
These switches have some major changes, the first of which is (although this is a bit hazy as to the full details) a LIMITED LIFETIME WARRANTY, which if true removes a major advantage from some of cisco's switching competitors. The new switches also use the new licensing model.

The other extremely exciting part of these switches which I can confirm is a SIGNIFICANT price drop for these models.

Let's examine some of the new features of the 3560/3750-X in more detail:

- The 3750-X is still the stackable switch, while the 3560-X is still a standalone switch
- Modular Network Modules for both 3560-X and 3750-X(See picture below:)

- Industry first 30W POE on ALL ports in a 1RU formfactor
- Stackable Power! Providing redundancy across switches for your power! This is probably my favorite new feature of all the enhancements

- Enhanced Stacking (StackWise Plus) Offering both backwards compatibility and 64 Gigabits Backplane! Also offers a new technology where by the switches do not have to use the stack ring to send traffic from local ports to another local port. Totally backwards compatibile with the original stackwise so your original 3750's can still be part of the stack.
- TrustSec Security, This needs a whole blog post in and of itself but is basically a way to encrypt traffic on the wire, its an enhancement to 802.1x
- Energywise technology reduces energy consumption by up to 50 percent

Next we have the 2960's (available at an excellent price point by the way):

- 10 Gig connectivity can now be provided by 2960's
- 30W+ POE Ports now supported
- True, hot-swap stacking via Stack modules for the new 2960!
- 15.4 Class 3 POE across all 48 ports when equipped with a 740W power supply

I am truly impressed by this latest announcement from Cisco, they have listened to exactly what the customer has asked for, seen what the competition is doing and have come out and done one better than them.

Monday, March 15, 2010

Blocking a call based on incoming number for CCME

Hey Guys

Something you might find useful, is that you can block incoming calls based on the calling number on CME.

Here is how i would block 0894110000 from being able to send its fax-spam

first create a voice translation rule to match:

config#)voice translation-rule 1
cfg-translation-rule#)rule 1 reject /0894110000/

apply this to a voice translation profile

config#)voice translation-profile blockSpam
cfg-translation-profile#)translate calling 1

finally, place this on your incoming dial-peer NOT with the normal way of applying a translation profile but with a special command called call-block

config#)dial-peer voice pots 100
cfg-dial-peer#)call-block incoming translation-profile blockSpam
cfg-dial-peer#)call-block disconnect-cause incoming call-reject

I hope this helps someone out there, Once when I first started in the VOIP industry I inadvertently helped someone setup there router to send fax-spam. I guess this is my attempt at forgiveness and help you work your way around it!


Tuesday, March 9, 2010

Super QUick Update (secondary dialtone)

Hi Guys

Just a really quick update: I am studying for my CCIE Voice at the moment (Yes I have decided to switch from Security simply because I do so much more voice and feel so much better about voice than I do about security. Rest assured i'll come back to security some day.)

Secondary Dialtone for CCME?

config-telephony#)secondary-dialtone 0

This will enable a secondary dialtone to be heard when a user dials "0" on CCME

Until next time!