Calling ID , Type and Plan

Hi ,

Just as a reminder when you sit in the lab, try to not forget to put the correct Calling number , type and plan and this for all situation so it is true as well for SRST.

So a good vision of the call routing is important

MGCP Bind L3 Issues

Sometimes , when you defined your mgcp config and before to activate it with the CUCM config. You can experience issue where you can not send or receive calls on this gateway only because your link is not up.

This is caused because the binding between the MGCP gateway and the CUCM is not properly set up. So in order to fix this issue under your serial interface , remove the command isdn bind-l3 ccm-manager and put it again just after. The result is direct and your PSTN will go up .

The Minimum MGCP configuration

Here is a basic stuff to implement the mgcp config

ccm-manager fallback-mgcp
ccm-manager redundant-host
ccm-manager mgcp

ccm-manager music-on-hold
ccm-manager config server
mgcp call-agent service-type mgcp version 0.1
mgcp bind control source-interface GigabitEthernet0/0.102
mgcp bind media source-interface GigabitEthernet0/0.102

mgcp profile default

Real-Time Fax

Real-time fax over IP operates in a similar way of a regular fax transmission. The fax machines involved in the transmission synch up and then the fax data is sent between them over the intervening IP Network.

There are 2 methods of transporting fax in real time across the network:



When using fax-relay, the T30 fax signal from a connected fax machine is demodulated by the sending fax gateway and sent over the IP Network to a remote fax gateway. The remote fax gateway then recontructs the T30 fax signal and send it to the fax.

There are 2 types of fax-relay mechanisms:

Cisco fax-relay

T38 fax-relay

Cisco fax-relay is an older method. So a fax gateway terminates T30 fax tones from a local fax machine and then sends the fax data across an IP network by breaking the tones into HDLC frames and then transmitting them using RTP.

T38 fax-relay is the ITU standard T30 fax signal, it is demodulated at the local gateway and encapsulated into IP packets for transport over a network to a remote fax gateway which will then reconstruct the signal and play it to the fax. T38 includes also a mechanism by which a fax gateway can inform the remote gateway of its desire to change the media type from voice to data. T38 can also use TCP or UDP connections but will use more UDP.

For fax pass-through, modulated fax data is sent in-band across the IP network by a fax gateway using a voice codec (like G711 without any VAD or echo-cancellation). Also with fax pass-through, T30 fax calls are not distinguished from regular voice calls, they are simply sent in-band over the IP Network. With the fax detection tones, the gateway must be able then to switch to high-bandwidth codec. Fax pass-through is relatively bandwidth hungry and is sensitive to delay,jitter and packet loss

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