Update the software. Newer phones come with the latest software or firmware. It always helps with the dropping calls, loosing signal, freezing, bugs, etc.
Most of the times its like this for every phone, the first models sold are kinda like beta versions, because then people compain and say whats wrong with them, then they come out with a better software/firmware after they have customers test the first ones.

Maybe your older phone only supports a certain Network Band (e.g. 1900), while the new one has support for several Frequencies (850, 1900, etc)

Some areas can differ with their network band even they are of the same Network Company.

may b some software problems in your phone

may be there is any problem with ur older phone. how could we tell about ur phones. it would be asked to ur phone destributer.

Maybe the first one was bad from the begining.

I had a situation happen to me sometime ago and I am wondering about what happened. I had a UT Star Comm UMUT1 also known as an Arc. The cell pouch fell from my belt and was lost somewhere along my walking route. I had to replace the cell phone with another UMUT1. I work in an office building that is like a Bermuda triangle for cell phone signals, nothing goes in or out. The older phone got cell signals in 0% of the office building while the new one gets singals in 75% of the office building.

While both cell phones are UMUT1s the new one got much better cell signals then the older one did. How come? I thought that in order to get better cell reception I would have to wait until UT Starcomm came out with a new model. Instead the model number did not change, they are both UMUT1s, but the newer one gets better reception. There is something going on here that I don not quite understand.