How to avoid awkward situations on the phone?

Hello e-babians… I'm currently working as a sales representative at a textile company. Since I'm working in foreign trade department I have to make phone calls quite often. I encounter awkward situations and I just don't know what to say.

Like when I do not understand what the other side is saying. This is especially the case when I'm talking to a non-native speaker. I could simply say "my english is not that good could you please explain in simple terms" or smt like that when an english or american is concerned. But what if I'm talking to a non-native speaker who speaks a terrible english? How could I say "Mr X, your english sucks, that's why I can not understand" in a polite way?

And I think I have a serious problem… What is this "_" character called in english? I really wonder that… I would choose to call it "long line" This came to my mind when I was talking to an official who doesn't know how to spell letters (when I asked his e-mail address)

And one more thing… My strategy is to send an e-mail to the prospective client with an introductory information about our company and the next day talk to their executives on the phone. My conversation goes smt like: "I just called to make sure that you received my mail, you know, sometimes spam filters block e-mail (what a subtle lie :) )... and then comes "what's your impression about our company" :) Do you think that is unethical? I just think that it is part of my job.

valued info.i usually come across this matter,but i can;t deal with it well.thank you for all of you.I will have a try.

www.bbc.com will help you i think

And one more thing… My strategy is to send an e-mail to the prospective client with an introductory information about our company and the next day talk to their executives on the phone.
See if you can set-up an appointment to talk to them; this shows you are courteous with regards to their time and may prevent a cold return. They can return your e-mail with a time and date that you can call. Remember, they are busy too.

My conversation goes smt like: "I just called to make sure that you received my mail, you know, sometimes spam filters block e-mail (what a subtle lie :) )
They will already know that and should have the ability to check their spam folders.

... and then comes "what's your impression about our company" :)
How will they have an impression of your company if they are not doing business already?
Ask this question after they become a client.
Instead, ask how your company can help in meeting their objectives.

Do you think that is unethical? I just think that it is part of my job.
I do not think it is unethical. See business ethics. Sales is hard work.