First off, the 5959 as far as I know is just a 2.4Ghz antenna. So if you just want to use the 802.11G radio, then you will not have any problems leaving your existing antennas in place.

However, if you want to use the A radio, then you're going to need to install new antennas in addition to the 5959's in place.

I'm not sure if your question was asking how important it is to deploy 802.11A, or if it was about replacing the antennas on the A radio (which you do not have, since you're current deployment does not have an A radio).

Well there's some discussion here about segregating 7921 voice traffic over on A. I've been told this is a best practice.

Mike

Merry Xmas

You can segregate your 7921 traffic to the 5GHz band, its usually alot less congested. the 5959 is designed and tested at 2.4GHz but will work on 5GHz however you then dont have a compliant system as the testing is at 2,4GHz and I am not sure what the equivalent dB rating would be. Also if we assume that it was 2dB on 5GHz its quite low and your cells will be small as 5GHz has less ability to propogate in the environment. As frequency increases signal propogation decreases. Advantages of 5GHz are 19 non overlapping channels and less interference. Typically you would have a 3.5dB antenna on 5GHz to give a similar RF footprint as a 2dB antenna at 2.4GHz

The 1231 is EOL june 2009, just announced and the 1232 wont be far behind. The 1242 is a much better option and is almost a like for like swap, just change the base plate

I must agree with the others about going with the 1242's. But before you decide on putting phones on the 5ghz, make sure you have enough coverage that you need. The reason I say this is that you currently have the 1230's and most likely only had a site survey done on the 2.4GHz, so if you are trying to cover a warehouse or something equivalent with racks, then you might need to reconsider a new wireless site survey to ensure you have adequate coverage fro phones on the 5ghz side. Either way you should verify the coverage before you get some unhappy users. The 5ghz antenna that is similar to the 5959 is the AIR-ANT5145V-R.