When you say you don’t have static IP’s in the UAE does that mean you have NONE? If you have at least one I would setup a sonicwall vpn. This can be done dynamically but it will need to use something DDNS. Once their is a sonicwall on each vpn endpoint you add the different networks together.
In my situation we have 192.168.0.0, 192.168.1.0, 192.168.2.0, 192.168.4.0 and 192.168.5.0 all of them are spread out across the world. There are at least 1.5mb connections between them. Your phone switch would need to utilize your lan via IP phones.
Depending on the amount of handsets is the size of the phone switch you will need, For a 10 line operation I recommend a talkSwitch but for anything more serious than that even though it is expensive I use Avaya equipment.
Once all your networks are on the network and your phone switch is set to utilize the network to get to the IP phones – you will be able to dial an extension in the good old US of A and hit the UAE for FREE!
Let me know if I can further elaborate. And here are links for the talk switch and Sonicwall.
You will need to also lock down QOS on your network so you can prioritize the voice traffic over the data. Or you can utilize seperate lines for this. On a T1 you can get 24 channels (calls) any more you can do the math yourself!
Anything else let me know!