Cisco Cisco IOS Software Release 12.4(4)T

a=cpar: a=T38FaxMaxBuffer:200

a=cpar: a=T38FaxMaxDatagram:320

a=cpar: a=T38FaxUdpEC:t38UDPRedundancy

*Jan  4 17:54:55.047 EDT: 

//53/0776534D8005/MGCP|S1/DS1-0/23|-1|-1/<VOICE>/mgcp_remove_old_ack(714):[lvl=1]Removing 

ack: (trans ID 1601) : 200 1601 OK

Review the following bullet items to verify compliance of your configuration:

STE devices operate over V.150.1 and VBD (FNBDT or STUIII).

IP Secure Endpoint devices operate only over V.150.1—there is no network-side DSP.

In Cisco Legacy V.150.1, if you configure an SCCP endpoint with the both keyword, that endpoint 
always uses modem pass-through when establishing connections to endpoints supporting both 
modem-passthrough and V.150.1 modem relay, such as other SCCP ports or MGCP-controlled 
PSTN trunks. If V.150.1 modem relay is desired, use the modem relay keyword when configuring 
STCAPP ports.

Use the modem relay keyword for STE devices to force V.150.1 when setting up STE-to-STE calls.

Make sure the global configuration voice service voip modem passthrough command is 
configured. This command provides fallback to VBD mode when your device is communicating 
with a legacy Cisco SCCP gateway or an STU on a gateway running the Secure Communication 
Between IP Secure Endpoint and Line-Side STE Endpoint feature.

Codec capabilities cannot be limited on an MGCP trunk. An MGCP trunk always registers with all 
supported codec capabilities.

This section provides information about some possible problems or issues that may arise when you are 
configuring and operating the Cisco V.150.1 MER feature. Review the information in 

 for 

symptoms and possible solutions to help ensure operability of the Cisco V.150.1 MER feature in your 
network.