Below is HP definition for the the error code.
It seems consistent with your description.
252 Telephone line conditions were too poor to receive a fax.
Do The following:
1. Check the telephone line for noise by connecting a phone to it. Press one key on the keypad and listen. A working line should be essentially silent. If you hear cracking or hum on the line call for service. You didn't mention whether or not the problematic fax is coming from one phone number. If your line seems 'clean' then the problem may be with the senders phone line.
2. Unplug the power source for 30 seconds.
3. Use a known good phone cable
4. Make sure the phone cable is plugged in securely on both ends.
HP officejet k60
