ayat,
look for the AGCH congestion rate and the PCH congestion rate. You can’t miss them, they are available per cell in the NPO.
Then, you can also monitor the AGCH radio load and PCH radio load. They should not exceed 60% (in theory), to avoid any possible blocking.
Finally, check the RSL load on the Abis : it is the physical channel that carries all those pagings. Look for : LAPD Congestion, in BTS object, or in Lapd object, I forgot.
Keeping only 2 AGCH blocks is rather low, focus especially on hourly AGCH radio load & congestion.
Regards
pix