If he's got BT, he is almost certainly on a BT Homehub v3. From a PC connected to a Homehub 3 via Ethernet or wireless, the way in to the modem is to open a browser and go to
bthomehub.home.
The modem stats are available by clicking these menus in turn:
Settings > Advanced Settings (admin user name and password required at this stage, if he hasn't set them up yet, the default ones are on the plastic tab slotted into the back of the Homehub) > Continue To Advanced Settings > Broadband > Connection.
You then see all of this:
ADSL Line Status
Connection Information
Line state: Connected
Connection time: 0 days, 03:33:03
Downstream: 2.938 Mbps
Upstream: 448 Kbps
*
ADSL Settings
VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.1 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 9.2 dB / 20.0 dB
Line attenuation (Down/Up): 59.4 dB / 31.5 dB
Output power (Down/Up): 18.8 dBm / 12.2 dBm
FEC Events (Down/Up): 612 / 23
CRC Events (Down/Up): 0 / 16
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 0 / 10
Error Seconds (Local/Remote): 55 / 100