SPAN or mirror ports are typically an Ethernet thing, not T1. You'll also have trouble monitoring everything if there are a total of over 23 active calls on both of the T1s. Not a problem in your specific case as only one will be active.
If the TA900 is used to convert from SIP to PRI, you're probably better off sniffing the Ethernet side for SIP/RTP traffic rather than the PRI side for TDM. Any managed switch on the Ethernet side with a mirror or SPAN port can do this, then you can use any of a number of programs to capture and record the calls.