Two modems involved here, one incoming, one outgoing:
1). USR013453B - Unfortunately this is not a revision C but a revision B modem so latest firmware available is 2.2.05, I will upgrade this from it's existing 2.1.1
2). 80-010955-01 - Can't establish from the USR site whether or not there is a firware update for this one or not, is is currentl on: Supp rev. 044-7.6.7 DSP rev. 3.1.2