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International Call Limitations and Risks

This article will explore the restrictions in place for dialing internationally to reduce the risk of fraud and paying high tolls.

Written by Adrian Angwenyi

Updated at June 19th, 2025

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Table of Contents

Blocked Countries Types of Telecom Fraud International Revenue Sharing Fraud (IRSF) Domestic Premium Rate Service Traffic Pumping Telecom Arbitrage (Tromboning) Interconnect Bypass

More Info: To view our list of how to dial internationally and our accepted International Country Codes for dialing, check out this article. 

 

WARNING: By default, SpectrumVoIP phones have international dialing Disabled in order to prevent accidental international fee fraud.
Please contact Technical Support if you would like International Calls Enabled on your phone. 

There is no charge to enable International Calling. International Calling fees only occur when International Calls are placed. 

NOTE: SpectrumVoIP may disable the ability to call certain global regions due to high fraud risk or if the rate is higher than our threshold. 

This is all in order to try to prevent fraudulent calls from happening.

 
 

 


Blocked Countries

There are countries that we block and will not unblock due to fraud and high tolls. 

According to the recommendations of Bandwidth, SpectrumVoIP blocks the following frequently “Fraudulent” countries from being dialed:

Initials Blocked Country Country/Area Code
AC  Ascension Islands 247
AG  Antigua/Barbuda  1 268
AI Anguilla 1 264
AS American Samoa  1 684
BB Barbados 1 246
BM Bermuda 1 441
BS Bahamas 1 242
CD Democratic Republic of the Congo 243
CF Central African Republic 236
CG Congo 242
CZ Czech Republic 240
DM Dominica 1 767
DO Dominican Republic 1 809
1 829
1 849
GD Grenada 1 473
GQ Equatorial Guinea 240
GU Guam 671
HT Haiti  509
JM Jamaica 876
KN St. Kitts & Nevis  869
KY Cayman Islands 1 345
LC St. Lucia 1 758
LT Lithuania 370
MA Morocco 212
MF St Martin 590
MP Northern Mariana Islands 1 670
MS Montserrat 664
MV Maldives 960
PK Pakistan 92
PW Palau 680
SC Seychelles 248
SX Sint Maarten 721
TC Turks and Caicos Islands 1 649
TD Chad 235
TN Tunisia 216
TT Trinidad and Tobago 868
UG Uganda 256
VC Saint Vincent and the Grenadines 1 784
VG British Virgin Islands 284
VI U.S. Virgin Islands 340
SL Sierra Leone 232
SD Sudan 249
LR Liberia 231
LV Latvia 371

 


Types of Telecom Fraud

While there are almost too many different types of telecom fraud to list them all, there are five (5) main types that we, and our users, see most often:

  1. International Revenue Sharing Fraud (IRSF)
  2. Traffic Pumping
  3. Domestic Premium Rate Service
  4. Interconnect Bypass
  5. Telecom Arbitrage (Tromboning)
     

International Revenue Sharing Fraud (IRSF)

International Revenue Sharing Fraud utilizes technical means to make unauthorized calls to premium numbers with high tolls/fees. To do this, cybercriminals and fraudsters use hacked IP phones, stolen SIM cards, and compromised Public Branch Exchanges (PBXs) to direct calls to their own or leased lines to bill those incoming calls. 

To prevent these kinds of attacks, passwords for the IP phones' web user interfaces are not handed out unless certain special conditions are met by the requester for this information. 
 

Domestic Premium Rate Service

Much like IRSF, Domestic Premium Rate Service relies on parts of the U.S. being more expensive to complete calls to. 

Rural parts of the country can be more expensive to call, so fraudsters commonly use this to intercept and route calls to these more expensive areas to collect larger fees.
 

Traffic Pumping

Traffic pumping happens when fraudsters utilize automated phone-answering services to generate traffic in expensive areas of the country to complete calls. They then advertise these numbers (often via social media) to drive calls into their system. 

Callers are met with dead air, barking dogs, or ‘press 1 to continue’ loops to extend the length of the call to maximize the amount of money they can charge for these calls. 

Sometimes a nefarious service provider could be involved. These bad actors will overcharge reputable carriers with exaggerated access charges with a portion of these fees given to the fraudster.
 

Telecom Arbitrage (Tromboning)

Telecom Arbitrage, also referred to as “Tromboning”, happens when telecom companies utilize and provide long-distance access numbers that route calls through a third country as a middleman in order to falsely present themselves as offering lower settlement rates to attract customers. 

What these customers do not realize is that this strategy earns the telecom company higher interconnect fees while also putting the customer at risk for fraud and unwanted robocalling. 

Operators can combat telecom arbitrage by ensuring they only resell minutes to reputable companies and keep a close eye on their partnerships with third parties.
 

Interconnect Bypass

Also referred to as OTT Bypass Fraud, interconnect bypass fraud is based on legacy interconnect telecom systems. Fraudsters will sell long-distance calling cards to be used by unsuspecting customers. When a customer calls this number provided to them, their call is redirected to another Carrier's network to make the call appear like a cheaper, domestic call to bypass the normal payment system for international calling. In reality, the Carriers that are given this redirected traffic take on those fees/tolls. 

Due to how this fraudulent activity works, customers are not usually impacted since the affected carrier ends up accepting the fraudulent charges.


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