mtp required on cucm

Answered Question
Jan 30th, 2013

i have CUCM 8.51 and have a lot of sites that are on SIP Trunk.  I currently have Media Termination Point Required option checked on the SIP Trunk.

It works fine but it inserts mtp on all in/outbound calls.

Starting CUCM 8.5, I can use Early Offer support for voice and video calls (insert MTP if needed) option under SIP Profile instead of MTP required option checked.

I like this feature but never tried it.  Anyone out there have used/using this new feature?  To configure it, do you simply uncheck MTP required option unchecked and simply check Early Offer support for voice and video calls (insert MTP if needed) option under the SIP Profile?

Is there anything i need to check before i enable this new feature?

any help would appreciated.

I have this problem too.
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Correct Answer by Ayodeji oladipo... about 2 years 3 weeks ago

The 7962 phones support both RFC833 and OOB so you wont need MTP for DTMF for them.

You dont need to make any changes..Once you set this, its ready to go..

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Chris Deren Wed, 01/30/2013 - 08:33

Do you have direct SIP trunks from CUCM to ISP or do you use CUBEs? If you have CUBEs there was never reason to have MTPs, if you have direct SIP trunks from CUCM then with early-offer support on CUCM you should be OK.

HTH,

Chris

vatter Wed, 01/30/2013 - 08:53

Thanks for the reply Chris.

I use CUBE.  When i used the SIP trunk without MTP required option enabled, i was getting a lot of issues. For example, unable to transfer, call drops, etc..  As soon as we enabled MTP required option, all the issues went away.

We also have a lot of older type A phones(79x0) and most of type B phones(79x1,79x2,79x5) are running SCCP.

i have software MTP configured on the CUBE and it is doing DTMF and EF/DF conversion.

Do i still don't need MTP since i have a CUBE?  If it is true where do i insert mtp for older phones?

Ayodeji oladipo... Wed, 01/30/2013 - 12:33

Vatter,

You do not need MTP to do DO to EO on the CUBE. CUBE does it natively. All you need to ensure is that you have early offer configured on your CUBE. MTP is o nly used to do EO on CUCM not for DO to EO.

Yes the Use MTP required works very well and that will only use MTP for calls that need MTP for either DTMFetc.

You also dont need MTP for supplementary services for a sip to sip call topology. What IOS version do you have? Are you using sip all the way? or do you have h323 iny our call flow...

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vatter Wed, 01/30/2013 - 12:47

Here's what i noticed on my system.  When MTP required is checked, it inserts MTP for all in/outbound calls.

Do i uncheck MTP required and check insert MTP as needed option in order for the system to insert MTP as needed or check both?

Do you need MTP if sccp phone calls out bound calls out to SIP trunk?

We have 2921 CUBE with 152-3.T2 code.

Ayodeji oladipo... Wed, 01/30/2013 - 13:09

Yes you should uncheck MTP required! With CUCM 8.5 you s hould leverage the use of MTP only when required..not for all calls.

On SCCP phones. The 7960/7940 models do not support RFC833..Hence they will need MTP over a sip trunk configured for RFC833..

Here is the SRND guide..From the SRND

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/8_6_1/ccmsys/a08sip.html#wp1123688

Media Termination Point (MTP) Devices

You can configure Cisco Unified Communications Manager SIP devices (lines and trunks) to always use an MTP. If the configuration parameters are set to not use an MTP (default case), Cisco Unified Communications Manager will attempt to dynamically allocate an MTP if the DTMF methods for the call are not compatible. For example, phones that are running SCCP support only out-of-band DTMF, and Cisco Unified IP Phones using SIP (7905, 7912, 7940, 7960) support only RFC2833. Because the DTMF methods are not identical, Cisco Unified Communications Manager will dynamically allocate an MTP. If, however, a phone that is running SCCP that supports RFC2833 and out of band, such as Cisco Unified IP Phone 7971, calls a Cisco Unified IP Phone 7940 that is using SIP, Cisco Unified Communications Manager will not allocate an MTP because both phones support RFC2833. By having the same type of DTMF method supported on each phone, no need for an MTP exists

CUCM by default will dunamically insert MTP when it is needed in this case. Another thing you should do is set your sip trunk dtmf to "no prefrence"

try this an if you have issues with supplemetary services etc, then we need to look into what is going on..

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vatter Wed, 01/30/2013 - 14:24

Thanks for the clarification. I went through that document many times and I am still unclear of few things.

I was on the phone with a Cisco TAC, he told me I needed to check both MTP required and MTP as needed option.

I read release note and it says I do not needed to check MTP required and i think release note is correct.. but I wanted to check before I start making changes.

Do I need to change any parameters in the system setting when I make this change?  i will uncheck MTP required and check Inert MTP as needed uner the SIP profile.

On SCCP phones. How about 7962 phones that are running SCCP, do I still need MTP for out bound call?

I thought it will need MTP because SCCP will only do out of band thus CUCM will do the conversion and send calls out to the SIP Trunk.

thanks,

Correct Answer
Ayodeji oladipo... Wed, 01/30/2013 - 15:47

The 7962 phones support both RFC833 and OOB so you wont need MTP for DTMF for them.

You dont need to make any changes..Once you set this, its ready to go..

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