Verizon has the biggest 4G LTE footprint in the U.S., but its 4G phones so far have been limited when users traveled overseas. For roaming, they have relied on 3G CDMA technology, which reduced their travel range to about 40 countries.

Now, along with an upgrade to Android 4.0, or Ice Cream Sandwich, Verizon is pushing out software that activates the GSM radios in the two Motorola smartphones. As soon as subscribers get the update, which started going out Friday, they can use international roaming in about 150 countries.

Occasional travelers can talk on foreign carrier networks at rates ranging from $0.69 per minute in Canada to $4.99 per minute in Kenya, Sri Lanka and several other countries. A $4.99-per-month Value Plan reduces those rates. Data roaming, on networks with speeds up to 3G, costs $0.02 per kilobyte or $20.48 per megabyte in most countries, or $25 per month for 100MB.

Subject to restrictions, Verizon can also allow subscribers to go to a foreign carrier and buy a new SIM card to replace the one in their Razr or Razr Maxx, spokeswoman Brenda Raney said. They would then pay the foreign carrier's rates, while also relying on that carrier for support, she said. Verizon subscribers can't use the phones on GSM-based carriers in the U.S., she said.

The two Motorola phones are equipped with radios for GSM in the 850MHz, 900MHz, 1800MHz and 1900MHz bands, and for 3G HSPA in the 850MHz, 900MHz, 1900MHz and 2100MHz bands, Raney said.