[cisco-nas] Problem with USR V.92 users - Bell Nexxia

[Aaron Leonard]

> We've been getting numerous complaints from users unable to
> connect to our AS5300 infrastructure.
> The IOS change was prompted due to the Cisco Vulnerability
> announcement.

> We were using C5300-IS-M 12.2(2)XA5 running 2.9.4.0 Mica
> modem firmware.
> Now C5300-IS-M 12.2(2)XB11 running 2.9.4.0 Mica modem
> firmware is being used.

> The engineer which "forced" this upgrade (Dan Fraser - Bell
> Nexxia) implied we shouldn't have any difficulties, however,
> we're now getting multiple calls involving USR V.92 modem
> users not being able to connect.

> In some cases "AT+PIG=1+PQC=3+PMH=1" on the client modem
> works, in others we have found no work around.
> Once again this seems to be affecting only USR V.92 devices
> (only one other report about a PCTel onboard modem problem).

> Francisco

This is probably what's going on:

By default, MICA portware 2.9.4.0 will enable V.92 only if IOS 
tells it that it supports V.92.  12.2XA5 will NOT tell MICA that
it supports V.92 (even though it does), while 12.2XB11 does tell
MICA that it supports V.92.

Therefore, by default, MICA V.92 will be enabled in XB11 but
disabled in XA5.  So, if you have USR clients with a buggy
V.92 implementation, they would now need to reconfigure or upgrade.

Your alternative would be to disable V.92.  Here's a modemcap for
2.9.4.0 to disable V.92 and V.44 - this should behave like 
2.9.4.0 did with 12.2XA5.

modemcap edit noV92orV44 misc &F&D2S0=0S29=6S21=3S34=18000S40=10S10=50 

Regards,

Aaron