6dB or below is bad and will experience no synch or intermittent synch problems
7dB-10dB is fair but does not leave much room for variances in conditions
11dB-20dB is good with no synch problems
20dB-28dB is excellent
29dB or above is outstanding

Loop Att. is Line Attenuation
Measure of how much the signal has degraded between the DSLAM and the modem. Maximum signal loss recommendation is usually about 60dB. The lower the dB the better for this measurement.
20dB and below is outstanding
20dB-30dB is excellent
30dB-40dB is very good
40dB-50dB is good
50dB-60dB is poor and may experience connectivity issues
60dB or above is bad and will experience connectivity issues

Output Power
How much power modem (upstream) or DSLAM (downstream) is using. Maximum recommended is about 15dB. The lower the power the better for this measurement.

Here is a quick run down on the various versions of skype compatible applications and an explanation of exactly how they go about making calls.

For the purpose of this explanation Im going to exclude the use of WIFI as a carrier simply because Im trying to understand whether making or receiving a Skype call on my mobile without WIFI is going to cost me.

Also for the purpose of this explanation the word free, only means free if its being referred to as part of your inclusive voice and data allowance available on your mobile’s contract. For example my current contract might give me 500 minutes a month and 1GB of data. So according to the Telecoms industry this is referred to as free. In my case I have to pay ¬£30 a month for the 500 free minutes and 1GB of free data. The Telecoms industry have abused the english language to suit their advertising speak so I guess will have to get used to it.

(scenario 1) Make and receive free skype to skype calls
The only way of making and receiving free skype calls at the moment is to use a mobile with skype built in such as the 3 Skypephone S2
This solution transmits the calls voice over the ip network and is therefore a true VOIP solution. In my opinion this should be the only scenario available. The alternative way of achieving this scenario is to use the skype client called Fring available here
Fring allows you to make and receive calls over your internet data plan. Fring also allow you to sign into numerous social networks simultaneously such as MSN Messenger, ICQ, Google Talk, Twitter, AIM and Yahoo! buddies. The only downside is that for some reason the call quality is not as good as using the skype client. Im not sure why this is but think its probably because the call is being redirected through another server.

(scenario 2) Make free skype calls and pay for receiving skype calls
This solution allows you to make free outgoing skype calls because the mobile devices skype client dials a normal landline. Your Skype call is therefore carried through the normal channels just as a voice call probably to a datacentre where it is then channelled down the internet to its destination.
If you have free minutes as part of your mobile contract then this call well be free. You skype client will also use a small amount of data to let the server know you are online and whether your about to make a call.

(scenario 3) Pay for making and receiving skype calls. This is where you use skype without having any call plan which gives you free minutes. There is no benefit to using your mobile as a device to make skype calls in this way except that you can contact other skype users which you would not be able to do without using a skype client.

The big issue with being able to make and receive free calls using skype is whether or not you can make the calls and receive the calls over your mobile devices data network.

Most devices are capable of making and receiving calls using the data network but, a lot of devices are disabled for many different reasons.
The main reason that mobile devices have restrictions put on them is that if you can make a free call then your not going to need to pay for it, which means the companies are not going to make so much money.

There are various ways to re-enable mobile devices to make and receive calls using the data network.

IPHONE & SKYPE

For those iPhone 3GS owners you can purchase a 3G unrestrictor app to allow Skype to work over the 3G data network. This works by tricking applications into believing they are on WiFi, even though they are on 3G or EDGE.

If your an iPhone 3G owner then you can jailbreak your iphone and install VoIPOver3G via Cydia, and it will automatically hack Skype to work over 3G data network.

If you live in the United States your onto a real winner because you can subscribe to an unlimited Skype calling plan for $3 a month and make unlimited calls. In the United Kingdom you can get a similar calling plans for landlines but beware of the Skype to mobile rates. They are whats commonly known within the consumer market as a “RIP OFF!”
At the time of writing this I think its about 0.16 GBP to call a United Kingdom mobile from Skype. This is also the price you yourself will pay for receiving a Skype call on your Mobile unless your setup like (scenario 1) described above.

A note on Jail-breaking your phone.

If you jailbreak your iphone you will invalidate your warranty and the EULA which you signed when you purchased your iphone.

Jail-breaking your iPhone is the term which refers to disabling the restriction which prevents you from installing un-licensed application on your iPhone. There are several strong underground scenes which develop and promote application for the iPhone. A lot of these underground apps cannot be found on the iTunes App Store. To date the easiest way of Jail-breaking your iphone is through this website http://blackra1n.com>