In this chart there are five banks quoting slightly different bid and offer prices. This may not always be the case. Banks trading in the same market might do this to distinguish themselves from the competition. The caller then has the opportunity to take the best price available. 
The best bid and offer prices are highlighted in the chart. A caller can quickly see which bank is quoting the best price.
Best Bid
If the caller wanted to sell GBP for USD, the best bid price is 1.6513 from RBS. This is the highest amount of USD they would receive per GBP.
Best Offer
If the caller wanted to buy GBP, the best offer price is1.6515 from Lloyds. This is the least amount of USD that they would have to pay for their GBP.
Nothing Done
If they do not like any of the prices they can also press the “Nothing Done” button.

Bid-Offer Spread  

In the quotes shown in the FX group chart, notice that some banks are quoting a spread of five pips between the bid and offer price (for example, Barclays is quoting 1.6511-16) while others are quoting four pips (for example, HSBC is quoting 1.6512-16). If a market maker can operate with a big spread – buy the base currency at a low price and sell it at a high price – this gives it a greater opportunity to make a profit.
Conversely, price takers are looking for smaller spreads. This indicates that the price taker is buying the base currency at the cheapest price and/or selling the base currency at the highest price. A balance is struck when price takers deal on the prices and the bank still has an opportunity to profit from the trade.
Effective Spread
The best bid/offer spread in the group chart is four points but because there are a number of banks quoting different prices, the effective spread is the difference between 1.6513 and 1.6515 which is only two pips. It is this availability of multiple quotes that makes this type of electronic trading attractive to companies.
Callers must have accounts and trading limits established with all of the banks with whom they trade. Only quotes from those banks with whom these arrangements are in place will show on a multiple quote trading screen.

Voice/Telephone Trading

Spot price deals can be entered into an electronic trading system. However, there are three reasons why a client might telephone a bank to ask for a price rather than dealing electronically.
Voice/Telephone Trading: Verbal Trading Jargon
There are some specific expressions used when trading verbally in the FX markets. To illustrate this we will look at a simple spot trade and then describe the various expressions that could be used.
Brunswick Papers, a company based in Hong Kong, needs to acquire about USD 10 million after agreeing a major purchase. The company contacts an FX dealer to work on its behalf. The dealer contacts Big Bank’s FX desk about purchasing USD 10 million. In this case, Brunswick Papers are taking or lifting the offer price. On the right is a graphic depicting how this trade may be transacted using voice trading.
Trade Conversation:
Market Maker: Big Bank FX desk. How can I help?
Price Taker: Can I have a USD/HKD in 10 please?
Market Maker: 83-84
Price Taker: Mine
Market Maker: Paid. I sell 10 mio against HKD at 7.7584, standard payment instructions.