Cheap phone calls
First of all, try to pay with anonymous vcc and try to give as little real information as possible when signing up.
VO-IP numbers, with decent prices. But unfortunately get blocked by some companies like HP. If you want to use skype I would go for the unlimited subscriptions if you are serious about SEing.
You can get 50% off by signing up for a subscription, then canceling it. They will offer next month free of charge.
This is good to stay anonymous because you can use any device to make calls. You can also buy a phone number, but wouldn’t recommend.
I personally never used this before, but got it recommended many times because of their low price/min, your own phone numbers for phone verification and solid privacy.
Very helpful, because you can call for free to USA/Canada, the only issue here is again, that some companies block the calls. Also you will need to buy a FireRTC account that can call to toll-numbers.
Anonymous wise FireRTC, is the best in the list.
You can use your own phone for local SE’s because most of the time it’s free and you already have a subscription, but this is totally at your own risk, don’t do 20 HP SE’s with your own cellphone.
Use whatever you like, every way has Pros/Cons, upto you to decide.