How should I call my existing customers to chat?

I have a software as a service and few hundred Paypal subscribers with phone numbers. I have heard its a good idea to talk to my customers so I can improve my product but I'm having trouble getting up the courage to call them. What if they don't speak English or the person on the line doesn't know what I'm talking about? What should I ask? How do you structure these calls? Should I have a question list ready? At what local time should I call them? (Many users use their home information for their Paypal account, even though the purchase is for work).

What is your experience with calling existing customers to chat?

I do recommend emailing them in advance, with a brief note that you would like to speak briefly at their convenience, to get their insights to improve the service, for how long (and possibly offer a nominal honorarium, say a $10 gift certificate to Amazon.com). I find end users are honored to talk and will make the time. I actually find these short calls better at training than longer dedicated training sessions.

Simply offering a list of times you're available is fine. Absolutely do send an invite in Outlook or Google Calendar when a time is picked. If you find this a recurring thing, then to minimize difficulty, consider an online scheduling service (e.g. doodle.com or genbook.com).

Calling out of the blue could be awkward for the customer, and risk you sounding like a telemarketer.

I like GoToMeeting that provides VoIP and phone numbers in every country. Join.me has great sound quality but VoIP only.

If your SaaS is US and English based, you can write the note in English and suggest US hours. If international, and the app is internationalized, try to contact customers in countries where you speak the language.

Write out a brief discussion guide and then feel free to follow each conversation as it goes.

I have spoken to a few people who have had significant success using Intercom to directly communicate with people via email whilst they are using their site. This has the advantage that you have some insight into what they have been up to (you can see various data about them), and you can overcome the issue of people being busy or having poor english.

I have no affiliation with the company at all, BTW.