Don't use her telephone number. Write her first via postal mail, and introduce yourself. Ask her permission to call. Ask her what times, dates, and telephone numbers are best and most convenient for her to receive your call. If she agrees then your call will be welcome indeed.
Emails are extremely impersonal.
Most women especially those with free email accounts change them regularly as they start to receive spam and abusive messages. Introduce yourself nicely via postal mail with enclosed photographs. Once your sincerity is established, then emails work well. Don' t drop in. If you are fortunate enough to travel overseas you probably will get a wonderful opportunity to meet your pen pal in person.