As you have guessed, fop and fop2 both track device names. If your connection between asterisk and the tenovis is not static, then you won't be able to monitor calls. If extension 1000 in tenovis maps to DAHDI/13, then it might work, but if the DAHDI channel varies from call to call, then you are out of luck.
FOP1 can monitor using regexps or clid, but I do not think you will be able to pull a full working fop or fop2 in your scenario.
Best regards,
