I don't see it as an issue - I used to ten key, back in the old pre-scanner cash register days, and my muscle memory for that was just fine; 60+ items per minute. I also dial a phone by touch. No muscle memory issues for either. It comes from association, I never associated a phone number with a register, calculator or number pad on a keyboard; and never associated calculator (etc) issues with the phone.
If you want to practice typing in phone numbers, just punch them into the cell phone, and NOT hit send. You get a visual feedback, as the numbers show on the screen. That, or invest a few dollars in a cordless phone with the same feature.
You'd be surprised at the human body's ability to adapt to two separate layouts, and yes, spacial memory DOES work that way. At least for most people.